You can always restore your backup data on TeacherKit.
(In case you don't have one, here is how to backup your data).
How to restore your backup on TeacherKit:
Tap on the sidebar, and go to "Settings" > "Backup"
You can restore your backup by just tapping on "Restore Data" button and selecting the backup you want to restore from the list of backups, tap on it and install.