We all burn out. If you're just bored with certain types of characters then run the opposite. Just like real people, some of my characters I take a liking to more so than others; maybe your GM can be flexible enough to let you try a couple different things to see what gets your interest.
On the other hand, if gaming itself is the problem then maybe you need to take a break from the dice altogether. Sometimes that's what it takes, and you've been gaming regularly for a long time.
I have a tendency to push myself too far, staying in something until I'm totally burned out, then I am unable to get near that activity for a long time. I stayed in a dead-end campaign before just because I was gaming with close friends, and reached the point I wanted my character to die. Too much. For several years after that I didn't game at all. That made some of my friends angry but I just couldn't do it.
As Clint once said, "A man's got to know his own limitations." Remember, it's supposed to be fun.