I want to have an enemy that respawns even after it dies.
That is, you're supposed to run away from the fight cause it'll just keep respawning even when you kill it.

The battle events don't seem to run if I kill all of the enemies though.
Is this possible without making too many changes to the scripts?

EDIT: found a solution. I added additional "setup_battle_event" calls before the end of the battle sequence (so that it will call any events before checking whether the enemy party is all gone).

Now anything that should occur when the enemy dies, and is the only enemy left, will occur.
I haven't found any other way to deal with this though.

I don't know if there is any other way, short of changing/adding a script. In theory, once the enemy's HP has hit 0, the game is over.

you could create a duplicate of the monster, similar to a final boss warping to another creature once you defeated the first form. However, keep the monsters looking alike, same stats and all, and see about creating a looping event so that they trigger each other back and forth. Not sure if that will work though.