WASHINGTON — All-Star second baseman Jed Lowrie knows the drill. He went through this before. At the end of the 2014 season, everyone seemed convinced — including Lowrie himself — he wouldn’t return to the A’s as a free agent.

Four years later, he’s heading toward free agency again, but it’s different this time.

There’s a chance he’ll stick around, and he’s encouraged by the possibility.

“I can say definitively they didn’t express any interest the last time around,” Lowrie said, “and they’ve expressed interest this time.”

Is the feeling mutual?

“Absolutely,” Lowrie said. “I enjoy playing with these guys. It’s a great core of players. I’m not going to take any option off the table.”

In December 2014, the Astros signed Lowrie to a three-year contract worth $23 million. In the next offseason, Houston traded him back to the A’s, who picked up a fourth-year option for 2018. At 34, he’s enjoying a career year — hitting .285 with 16 homers and 62 RBIs — and is a first-time All-Star.

After three straight last-place finishes, the A’s are playing like contenders. They’re 13 games above .500 after going a majors-best 21-6 the past month.

An issue is Franklin Barreto, the supposed second baseman of the future who has split time between Triple-A Nashville and Oakland this season.

Lowrie is hesitant to predict his future, saying, “I mean, if you listened last year, everybody was saying 100 percent I was going to get traded. Who knows what’s going to happen?”

Treinen-Doolittle reunion: A’s closer Blake Treinen returned to Nationals Park, his baseball home until the A’s reacquired him in a trade last July.

Last July, the A’s sent Sean Doolittle and Ryan Madson to Washington for Treinen and prospects Jesus Luzardo and Sheldon Neuse.

ALSO: All-Star Blake Treinen on playoff race: 'Why not the Oakland A's?'

“I don’t think there’s ever been a question about his stuff,” Doolittle said of Treinen. “It’s really come together for him. I’m so happy for him.”

Doolittle and Treinen were together in the 2011 instructional league with the A’s. Doolittle had just transitioned from a hitter to a pitcher, and Treinen recently had been drafted by the A’s.

Now they’re both All-Stars.

“When BoMel texted me to congratulate me on the selection,” Doolittle said of A’s manager Bob Melvin, “I told him I was going to try to find Treinen and see if I can pick up any tips.”

John Shea is The San Francisco Chronicle’s national baseball writer.