When using Prêt-à-Template, make sure the app is connected to your iCloud account. This is important because iCloud keeps your sketches safe when you change devices, delete the app, or if any error ever occurs. You can also sync your projects across all your devices using the same iCloud account.
Prêt-à-Template will ask your permission to use iCloud when you first open the app after installing it. If you don’t remember having accepted it, or might have denied it, here’s how to enable iCloud.
On your device, go to Settings and scroll down until you find Prêt-à-Template. Tap on it and check if “Use iCloud” is turned on. This way, you'll always have a backup to your sketches.