After experiencing this frustration a few times, I figured I would suggest a solution to this problem.
Basically; I find it unreasonable that a vampire count/undead general can keep respawning a base army perpetually after losses while sieging a settlement. The vampire count can repeatedly siege a lord in a settlement preventing recruitment of a substantial army to combat the vampire count, while also consistently losing battles where the defending lord comes out to fight them.
E.G. Vampire count sieges a city, we win a Pyrrhic Victory, and destroy the vampire count's entire army. The vampire count is then able to respawn 6 units including himself at 1/2 HP, and is ALSO able to move on very next turn after a complete annihilation (and death of the lord). The vampire count then uses this movement to re-siege the same city and prevent any recruitment of units by the defending lord. We then defeat the vampire count AGAIN with substantial casualties to the remaining army. Now, the vampire count is able to respawn a larger army than our defending force, and takes us out in a strait up assault of the settlement therefore WINNING the engagement because they LOST two battles in a row.
In essence the vampire count is getting a free recruitment of 6 half-health units without any time or money (undead, makes sense for money) penalty. It would perhaps make more sense if the defeated respawning vampire count was forced into a form of encampment stance for where they can still respawn their army, but not abuse the fact that their losses are essentially meaningless.
Please, let me know your thoughts on this everyone.