The reason why you lose your cues/loops/grid is because the filepaths to the audio files changes see this tutorial:
Why cues, loops etc can disappear from your DJ software aka filepaths matter
easiest way to fix for now and in the future:
Don't let iTunes copy your audio files
for iTunes:

for Music:

And finally, if you're on MacOS then I've developed an app which will do what you're looking for.
Shareable backup from a Rekordbox or iTunes collection for back-to-back preparation and more