Maybe Luc Robitaille?
He averaged over 40 goals per season and over a point per game every season up until the lockout. He was a hair under those numbers in Pittsburgh with 42 points in 46 games in the abbreviated 48-game 1994-95 season, and that would be his lone season in Pittsburgh. After being dealt to New York, Robitaille's production would plummet, with 23 goals and 69 points in his first season there, then he'd struggle even more so in his second year there, with 48 points in 69 games, and was shipped back to LA for another flailing former superstar, Kevin Stevens.
Luc was 31 when the Kings reacquired him, and he missed a good chunk of games his first season back due to injuries, but he would have a bounce back season in 1998-99, netting 39 goals and 74 points. He'd follow that up with 36 goals and 74 points again, and in his last year here (before signing with Detroit), Luc would net 37 goals and 88 points.
He found a way to get better in his 30s. Teemu Selanne is another superstar who struggled for a few years, then came back strong after the 2004 lockout. Those are the two who immediately jump out at me.