Actually very easy. A little inconvenient, but easy.
Just go to settings>general>reset>reset all settings. This will undo the "forgotten" device and allow you to re-pair it. Be careful not to hit "erase all content and settings"..you just want to reset all settings. You will NOT lose any content or data, but u will lose all ur current settings. You will also lose ur icon layout. But that's about it. Much better then a full restored.