Lost data after OS upgrade... can someone help please?

I recently upgraded the OS on my 8330... I made sure to do a backup first in case anything went wrong. All my emails, sms messages, and calendar stuff came through just fine, but all the data I had saved in one of my apps (MySecretDiary) is now gone. I figured, no problem, I'll just restore the backup I made. Only problem is, the backup doesn't seem to contain the data in question, because even after the restore, I have an empty list. Is there any way I can recover the data in question or did I seriously just lose six months worth of stuff? Can I manually extract it from the backup file somehow? Can someone throw me a clue here?

The Desktop Manager does not back up 3rd party apps. It only backs up user data.

For future reference, I suggest using BBSAK to back up 3rd party apps.