No direct way, as the database has no idea what you want to do with your favorites descriptions, selection of talkgroups, or other favorites settings.
If you have favorites lists that contain pretty much direct duplicates of what is in the database, the way to do it is to delete that system that changed from your favorites list, and re-append it from the full database.
If you follow the changes in RR from the site, you generally know what things have changed. For those lists that are highly customized, I just manually make desired changes and ignore undesired ones.
You can also have lists that are just for updates, where you re-append them, and then use them to cut and paste changes to the ones you use.
That's pretty much what I do. Systems and talkgroups change infrequently. Some times when they do, it's a pretty big change (like going from Phase 1 to 2, or analog to P25) so the FL has to be re-done anyway.