If you're using V1:

1. Backup your progress via Dropbox. 
2. Delete Syntorial off your iPad.
3. Reinstall Syntorial from the App Store
4. Open Syntorial, and Log In via the Menu at the top left.
5. After you log in, Syntorial will ask "Can we collect usage information?". SAY NO.

If none of the solutions above doesn't work/apply, send us a Crash Report so we can find and fix the issue.