May be it's not the best advice, but as people say better to canter her on your own (without the race) and not fast, and teach her to obey, before doing racing. In fact keep doing such racing will teach her it's OK to run, so she may bolt on you with no-stop in other situation.
I know bunch of people trying to use harsh bits on running horses. It ended up in horses bucking hard instead of bolting. Not the best perspective either... :(