Force close your iPad and then open it. I do NOT want you to uninstall the game because you will lose all boosters and lives, I play on 2 iPads and an iPhone. If it doesn't work then just bring it in on your iPhone. You can only bring it in once on your account every so many hours.
I was playing bubble gum hill and soda froze, and when I reopened the game and went to bubble gum hill the game had sent me back to level 1 - very annoying!