Change something.
I have been burnt out of DMing D&D last year. I needed to do something else. I have gone into d20 Future and Grim Tales, leaving out all that Tolkien stuff of elves, dwarves, wizards, monks, halflings, and what not. New races, new rules (Grim tales), new setting (sci-fi, different heroic fantasy more low-magic), etc. I couldn't go anymore into D&D. Right now, I have gone again to D&D, but only as a player. Yet, i don't want to play elves, gnomes, and the like anymore. I am tired of them!
So my advice is to maybe play rather than DM. Then you can change setting, go for a very specific ambiance instead of everything-and-its-brother-together that is often D&D. Lastly you can change of game: there are many other d20 games (Conan d20, Black Company, Grim Tales, d20 Modern, d20 Future, Blue Rose, CoC d20, etc.), and also other non-d20 games.