Roberto Giobbi had some good advice about this subject in his "Ask Roberto" download from the lybrary. I think one of the things he mentions that you could do is that you draw and imaginary circle in front of you, and take ALL of your best moments and put them in there. Then before each performance you simply step inside the circle and just "take in" all of the best moments and experiences.
I may have totally butchered what he really said, but you get the general idea.
Another thing that may or may not work is one thing I remember Maurice Lamarche mention about when he would audition for roles. He would simply go into the audition with the attitude of not giving a crap. (If you don't know who this is. I'll give you a hint. Pinky and The Brain, Futurama, The Simpsons, Animaniacs, and a ton of other popular cartoons.)