Recover from expired iOS beta

If you are a registered iOS developer and running an iOS beta on your device, you may notice that the beta stops working after a specific date if not updated in time.

Luckily, you can still keep your data by using this unintuitive and not well documented method:

1. Download new, unexpired iOS beta ipsw from developer.apple.com
2. Connect device and open iTunes
3. Hold down option (alt) key and click on "check for updates"
4. Select downloaded ipsw
5. Device gets updated without loosing data