I have an 01 XJ Sport, I frequent these boards
http://www.jeepforum.com/forum/forumdisplay.php?f=11
You probably just disabled the beep and you don't even know it.
[quote:4fbcc]Press and hold the lock button down for 5 seconds.
Then while holding the lock button press the un-lock button.
You should hear a chirp.[/quote:4fbcc]
That should prolly do it, this was the response given for the same problem to a dude with a 99 sport.