There is one other place where enemies respawn (at least that you can get experience from).
In the ministry in Aleroth, as Zandalor tries to close some rifts that opponents keep coming out of, if you allow him to get attacked he will keep starting over, letting more opponents though. Eventually the experience drops to zero, though (at least for most of the opponent types), so it can be handy to level a bit (if you turn the sound down so you don't have to hear Zandalor complaining each time he restarts), but not for high level leveling.
With the opponents in Keara's fortress headquarters there is a minimum experience amount, so you can repeatedly click on the door to spawn opponents, to level as much as you have the patience for.
