How can we keep Ren Faire fresh?
This sounds like a job for peer pressure.  Perhaps the other players should have to vote on whether any particular performance is sufficient, with an understanding that doing the same old thing won't suffice.  Sing a new song, make up some new bellydance move, improvise a new reason for a tantrum... if players aren't doing it on their own, apply social pressure.  It doesn't have to be good, just new.

(I've never played Ren Faire, but I've seen games of Once Upon a Time get stale until the group applied social pressure to make people actually do something with the cards they play instead of just saying "and there was a prince there, and a horse, and a robber, and...".)