With "exporting a fresh version", do you mean to import my Itunes playlists agian? Well I already teied that.
Why would I mean import but say export? Of course do not keep importing the same thing that didn't work over and over again. That would be a waste of time.
I'm saying that, within iTunes, there is the function to export your library in XML format. Do that function again, however it is done. I cannot give you a step by step on that as I do not have iTunes and do not know how to make iTunes export the XML. I'll bet google does.
Then use the fresh, up to date version to create your MusicBee library.
Question, though. If you know what files these are and know that they should be in playlists and know which playlists they should be in, why not just add them to the playlists now in MB and be done with it?