I say this only partially tongue-in-cheek... Drink Bud Light for a few days. You'll get interested again.
Seriously though, pick a new style that you've always wondered about. One that changes your process in some way that is challenging. Maybe a decoction mash, a sour beer or something else completely different.
I get bored now and then too. When I do, I try to find a new recipe, process step or toy, uh I mean, necessary brewing tool, to spice things up a little. Sometimes I just put everything brewing related away and do some other hobby for a while but I'm always drawn back in in a couple of months.