I just noticed that my iPhoto lost all of the "Faces" data (reason unknown). It must have happened fairly recently. I sync the entire library with my iPad, and the faces are still on the iPad. And I definitely have Time Machine backups of the library on the computer (though I don't want to just restore to an earlier state because I've added photos since).

How would you guys recommend I go about restoring this data? If I have to, I can restore an earlier version of the whole library and open the library data file (it's just XML, right?) and manually copy data to the current file. I'm just curious what people here would recommend, if you're more familiar with the library format and all.