Entertainment Weekly reports that Garret will make another appearance on Burn Notice this season. No confirmation on the episode yet, but he was in Florida around the time they were shooting episode 7×08 (spoilers at the link).
From EW:
Dillahunt, who currently plays Burt Chance on Fox’s Raising Hope, was last seen in season 4’s “Hard Time.” In his upcoming appearance, the audience will find the unpredictable Simon NOT inside the maximum security prison where he has spent the past years. The big question: Who let him out?