Yes, you're understanding correctly that WEP will eventually run out over a period of time/uses
As for the WEP possibly being renewed after rearming/fueling, I'm not sure.... least I don't recall it renewing itself in the spitfire I , in. FSO this past Friday night when I had landed and reloaded...
There was a thread about this AH III WEP times posted in the aircraft and vehicles forum not to long ago, I even think hitech posted a list breaking down every planes total amount of WEP times, or something to that effect....
BTW- I been watching your other thread about how IAS/TAS is modeled in the game and if the pitot tub is functionally modeled... when I get to my computer, I'll try and give you a more detailed answer... I've just been waiting to see if anyone else would come along and do it..
Hope this helps
TC