Save and restore iPhone game and app data with DataDeposit
This app looks promising. It saves game and app data for restoration when an app is deleted. DataDeposit uses nothing else than Dropbox to keep those files.
I haven’t tested this, but this way you could transfer files from iPhone to iPad and won’t have to start your game progress from the beginning. In case this works: Awesome Sauce!
DataDeposit works (obviously) only on jailbroken phones. Get it from Cydia. (ModMyi repository)
via aptgetupdate (German)