The snapshot feature does exactly this - you'll never accidentally lose a patch you're working on if you use it.
Up to 5 snapshots of the full state of the patch are stored. When you load a patch and you have a modified one in the edit buffer, a snapshot is automatically taken. You can manually take a snapshot at any time by a press of the Save button. To bring up the snapshots page, hold Settings and press Save. You'll then see that they're all timestamped and you can recall any of them by pressing the "2"-"6" buttons. The "1" button recalls the current edit buffer.
You can read all about it in the user manual: "6.2. Snapshots". It's a super handy feature
