How can I restore a single app to my iPod Touch?

When I recently upgraded my iPod Touch to iOS 4.1, I had to re-sync all my apps and music. The thing is, only about half of my apps synced successfully. I wasn’t completely devastated and just downloaded the ones that really wanted again. There is one app that I’d really like back, but I will have to pay for it again.

Is there a way to just re-sync a single app back to my iPod? It is a game and has all my saved data on it.