Did that and still didn't work. When I deleted the new GA app (or when you delete any app) it asks if you want to delete all the data that comes with it. In order to delete any app you have to say yes, is that why it probably didn't work? I know I've backed up my iPhone within the last few months so it doesn't make sense to me why it's not there.
It should be OK to delete the app's data - it should be restored when restoring from backup. However, most people have automatic backups enabled, either over WiFi or when you connect the cable. If a backup has occurred since you upgraded GA it is almost certainly too late.