Most likely you needs this (as humpfrey said):
For Beginners - How to Get Back Existing Station Number in A Fresh Install
In case you have any trouble with fr24 settings, i’ve described them here: Installing dump1090 fa · wiedehopf/adsb-wiki Wiki · GitHub
(this will also fix fr24 settings if they are a problem, which doesn’t seem to be the problem in your case: Bundle install for dump1090fa · wiedehopf/adsb-scripts Wiki · GitHub)