Exporting USB playlists BACK to Rekordbox

I manually dragged tracks from my drive which rekordbox is synced to to a USB stick. Then I realized I wanted the same tracks and playlists I made on the USB to be on the drive rekordbox is synced to.

RB does NOT allow mw to do this but I'm sure there is a way as I do not want to resort to doing this manually. Any help?