This article explains how to do the back-up of an application that is installed in your Apple device and how to restore it.
- Open iTunes
- Go to File > Devices > Backup
- Open the contextual menu of the application you want to backup
- Select the Show in Windows Explorer or Show in Finder option
- Back up the file (*.ipa)
- Open iTunes
- Go to File > Devices > Restore from Backup...
- Open Windows Explorer or Finder application
- Drag & Drop the file (*.ipa) from Windows Explorer or Finder to iTunes