Jason Mewes, the prolifically profane half of the cinematic pair known as Jay and Silent Bob, is a changed man. Off-screen, anyway.

Over the phone from Los Angeles, the former hardcore partier talks softly, since his 4-year-old daughter is staying home from school. “She’s a little sick,” the lanky 45-year-old tells The Post. “I made her breakfast, and when we’re done talking, I’m gonna go out food shopping.”

He’s been married for 13 years and sober for seven — but he’s donning his knit cap and parka again to return to his long-running role as Jay in “Jay and Silent Bob Reboot,” Kevin Smith’s latest movie, out Oct. 15. Mewes is hardly bringing the responsible dad vibe with him — in the first five minutes, he drops trou in an homage to “The Silence of the Lambs” — but he does get a chance to expand his range beyond catchphrases like “Snootchie bootchies!” and elaborate riffs on sexual fantasies. In fact, he says, he’s learning to emote.

“What was nice this time was knowing I had to actually challenge myself a bit,” Mewes says. “I get a little teary in my scenes with Harley [Quinn Smith, the director’s daughter], because of our relationship.” In the film, Jay finds he’s got a special connection to her character — we’ll leave it at that, but the story arc is surprisingly sweet for Smith’s snark-heavy productions.

The comedy is the seventh in a series Smith calls the View Askewniverse, named after his production company. It follows the same cast of characters spawned by his first film: 1994’s “Clerks,” which revolved around quick-witted, low-earning aficionados of movies and marijuana. Smith’s dialogue is either funny or wildly immature, depending how you feel about d–k jokes, but it’s earned a cult following over the years, fueled in part by Smith’s loyalty to his crew.

Nobody is more indebted to New Jersey native Smith than fellow Garden Stater Mewes — they were pals before “Clerks” — who was initially cast simply because Smith found his foul-mouthed bravado amusing. “In ‘Clerks’ and ‘Mallrats,’ I was super nervous,” Mewes says. “I didn’t plan on acting. I was horrible.” Yet he went on to appear alongside a near-wordless Smith, who plays Silent Bob in almost all of his movies.

Their last pairing was 2006’s “Clerks II,” after which Mewes had a reckoning with drug addiction that led to more than one stint in rehab. In 2010, Smith created a podcast, “Jay & Silent Bob Get Old,” dedicated to weekly chats with Mewes about staying sober and — lest they get too serious — recounting Mewes’ craziest anecdotes. A frequent bit, “Let Us F–k,” involves Mewes pantomiming sexcapades in front of a live audience.

“The first three years it was really easy because I had so many stories to tell,” he says. “But now I’ve been married for 13 years, so there’s not a lot of different sex stories. And I’ve been sober, so there are no new drug stories.”

He’d been talking to Smith for years about doing another movie, but it was a slow and sometimes painful process. “I actually started asking him after ‘Jay and Silent Bob Strike Back’ [in 2001], but then things went bad for me and I relapsed, and then I got sober again,” he says.

The new film was shot early this year, with familiar Smith plot tropes and celeb cameos by Ben Affleck, Matt Damon, Craig Robinson and Joe Manganiello. Mewes plans to tour with Smith at film showings, and also has a solo stage show, called A-Mewsing Stories, about his druggy past.

“Being an addict, you can never say you’ll never do something, but I just can’t imagine disappointing all the people who rely on me,” says Mewes, who allows a small regret for the timing of it all.

“I definitely used to get the worst weed,” he says. “It was like brown, with seeds and stems in it. Now you can go into a store [in California] and get all this great stuff. I feel like if I make it to 95 I’ll be like, ‘Yeah, I feel like I can get away with smoking one doobie.'”