The pass doesn't expire and there's NO NEED to take the exam again, I doubt the exam system would let you take an exam you've already passed anyway.
If you're not going back to your original school be careful where you go. Despite the system being 'competency based' it's not really. There may be a school or two that'll try have you do the whole thing again. On this front it depends 'where you are.' You'll get a pretty good idea where you are the first flight or two.
Good luck and enjoy.