If TuneUp incorrectly "cleans" a song, you have the option of restoring it's original metadata at any time using the "undo" feature.
Underneath the Clean tab, click on the Undo icon.
- In iTunes, find the song(s) you want to "undo." Highlight them, and drag them into the "undo" window.
- Tuneup will display the track's original information. Click on the "Revert" button to process the changes.