More than five years ago, a Clinton confidant matter-of-factly described for me Hillary’s Plan. She would ­resign as secretary of state after President Obama’s first term, write a book and then run for president again.

Check, check, and, with Sunday’s official launch, check again. Her to-do list is complete.

She stuck like glue to The Plan, which required years of misleading blabber from her and Bubba that she hadn’t decided about 2016. Fish gotta swim, and a Clinton’s gotta run, so there was never an iota of doubt.

But time has marched on and the world has changed, making The Plan, and her, look stuck in the past. What the great Murray Kempton wrote in 1965 of John Lindsay’s first mayoral run — “He is fresh and everyone else is tired” — is not something anybody says of Hillary these days.

She’s been on the national stage for a quarter-century, though because of all the drama, it feels like we’ve lived through several lifetimes with her. Along the way, she’s reinvented herself more often than Madonna. While the spectacle of an aging hoofer trying to keep up with the kids is riveting, the kicks aren’t what they used to be and the odor of desperation is unavoidable.

A presidential campaign headquarters in hipster Brooklyn — really? Announcing on Twitter — really? As Joan Rivers might have advised: Oh, grow up!

The sweaty effort to appear fresh reinforces the suspicion that Hillary senses danger in the argument that she’s awfully close to her expiration date. It’s not merely a matter of age, though she will be 69 come next Inauguration Day, which would put her close to Ronald Reagan’s record.

The real issue is Clinton fatigue, a national exhaustion from having been-there-done-that too many times. Her husband’s popularity counts for something, but she’s already milked that cow dry.

She’s got to make a case that goes beyond just wanting the Oval Office. She’s got to earn it and I’m not sure she can.

Here’s another blast from the past — Monica Lewinsky is 41 and wants to reclaim her identity, making her a potential bombshell that could explode without notice.

The arrows, then, all point the same way: Hillary is past her peak and missed her best chance in 2008. Her two elections and eight years in the Senate had made her something bigger and better than a scorned first lady.

She was ready to make history and the country was ready to help her. Then along came that fresh-faced senator from Chicago with a better game plan and a more convincing claim on history, and the brass ring eluded her grasp.

Her pain was understandably acute, and her willingness to join his team couldn’t have been easy. Shuffling off to Timbuktu while the big decisions were made in Washington was another stab in the back. But she endured, and even played along with his cockamamie foreign policies, a mistake that continues to damage America and her reputation.

That bad run of experiences could have forged her character into something admirable, but her performance so far has been a disaster. Instead of re-emerging as a smarter and more focused force rejuvenated by defeat and exile, she seems to have learned nothing and changed not a whit.

She still makes ­baby talk about breaking glass ceilings and other coded references designed to get her Pantsuit Posse out of their chairs, but it feels like a re-enactment rather than the real thing. After each bad review and each new scandal, the prospect of another usurper emerging from the shadows must give her panic attacks. Déjà vu all over again.

Will the left’s new darling, Elizabeth Warren, jump into the race? Will Martin O’Malley steal Iowa and puncture her balloon of invincibility?

What about Obama — will he help her or dump her? What price will she pay if she breaks with him on Iran or Israel? What mischief is Valerie Jarrett making?

Hillary would be crazy not to consider all those scenarios and a dozen others, but her first steps are depressingly robotic. Raise more money, hire more advisers, parse and calculate, hide behind her Praetorian Guard, rinse and repeat.

She’s older but not wiser and only a groupie could think it’s working. She’s become a gaffe machine and showed a tin ear by continuing to give paid speeches until a month ago. Then came the email debacle, which evoked a universal “There she goes again” quality.

It brought back a souped-up carload of bad memories — her habitual secrecy, arrogance and, most damaging, dishonesty. If she had come out and simply said she set up a private server for government business because rules are for little people, she would have had the virtue of honesty.

But still constitutionally incapable of being straight, she concocted a silly lie about the “convenience” of carrying only one electronic device, which was promptly demolished when evidence emerged that she had both a BlackBerry and an iPad.

We still don’t know the full story of what she’s hiding in those emails, but already there are fresh wounds. Although no Democrat threatens her yet, recent polls in six swing states show that, in head-to-head matchups against a raft of Republicans, she is basically tied or trailing nearly all of them. She makes them all look good.

Most revealing, Quinnipiac University also asked voters in Colorado, Ohio, Virginia, Florida, Pennsylvania and Iowa whether she is honest and trustworthy. Only in Ohio were the numbers split evenly; everywhere else, either a majority or a clear plurality answered with a resounding “No.”

Given her long history, ­changing voters’ minds on something so basic as trust won’t be easy. Her best hope is to fire a withering barrage of mud against an incompetent Republican. Again, we’d be reliving the ’90s, with her spying a vast right-wing conspiracy behind every tree and playing the victim when it doesn’t work. Oh, what fun.

There is, of course, a long way to go until November of next year, and events, especially the growing world disorder, will likely reshape the campaign and the public mood numerous times. Like all the candidates, she’ll have to reshape her message, too — after she comes up with one.

So far, something about Hillary does not seem right for the present, let alone the future. Aides have been discounting the early going as a false measure, and assuring backers that she’ll right the ship once she launches.

Perhaps but she is taking on much more water than they had expected, and her margin for error is shrinking fast. The polls suggest there is a tipping point with voters and inevitable stumbles and scandals could make 2016 look like 2008.

It could be that she’s star-crossed, and the gods will conspire against her again. After all, as Mark Twain observed, “History doesn’t repeat itself, but it does rhyme.”