I'd go to Sears (or wherever else you get your tools) and get a screw extractor. Basically, it's a special bit that you drives itself into the bolt in a reverse direction until eventually it gets in so tight that it starts to back the bolt out.

That being said, I just about stripped the kickstand bolts when I removed them, so I'm not sure how easy this is going to be. Squirting wd40 or liquid wrench into the threads for a while prior to attempting this wouldn't hurt.

What track day are you doing?