How to move to a NEW computer without loosing precious app data?

I have two kids who both have 4th Gen iPod Touch devices running iOS 5. Each of my kids also have their own desktop PC's running Windows XP as well as the latest version of iTunes (version 10.5). Several months ago they both got new laptops running Windows 7 and I recently updated iTunes on these laptops to version 10.5 as well. All of the content on the iDevices (music, apps, movies video's, and more) is present (successfully copied / downloaded) on both their desktop PC and their new laptops - this also includes full iTunes authorization on every device and every computer! Their iPod Touch's are currently being synced excursively with their desktop computers but I want to switch both iPod Touch's over to being synced excursively with their laptops. I've searched throughout these forums and I keep encountering the same advice about right clicking the connected device, making a backup before wiping and restoring, then restore again from the most recently created backup. I've tried this but the all app data including games saves, games levels, and other personal data within the some apps is lost or simply not restored. Please understand what I'm asking. I know how to get apps back on the devices - but I don't know how to keep from loosing the data held within the apps. Is there a way to move these iPod Touch's to a new computer without loosing precious app data?

Thanks

Randy