Well, maybe it's not in 2k, just later versions.
I guess just do this: set aside some switches, however many you need for enemies in the zone. After each battle turn on that switch and make it a condition of the second page of the event. Then, at each exit to the zone, turn all those switches off between the erase screen command and the teleport. When you come back, they should respawn.
You can use the same switches for every zone.