Each DJ software uses its own proprietary way of storing DJ metadata such as cues, loops, grid/BPM, playlist(s) etc. If you want to go from one DJ software to another, you'll need conversion software.
Your original DJ software and its tracks are unchanged by this procedure. The same tracks can be used with the same cues etc in both the original (djay) and the target conversion (Rekordbox 6) software. Only when things are changed in one of them, conversion is required again.
DJCU converts from djay Pro AI (not the previous versions!) to Rekordbox. So it's possible to continue to use your djay set cues and loops in Rekordbox.
In all fairness from djay to Rekordbox, is not the simplest of conversions DJCU hast to offer, long technical story about how djay stores the track identification.
here is the tutorial: