Hi John,
the B2 can import/load playlists.
The format the B2 uses for each entry in the playlist is plain text.
For individual tracks
/{album artist}/{album name}/{trackname}.mp3 e.g. /Rolling Stones/Sticky Fingers/03 Wild Horses.mp3
or for whole albums
/{album artist}/{album name} e.g. /Morrison, Van/Astral Weeks
This mirrors the way the B2 organises music files on its hard drive
If you can export your existing playlists into text files in the B2 expected format then you may save yourself time but you will need to make sure that when you rip or load your files to the B2 that the file names align.
Not something I have done I'm afraid
John