Hmm, that reminds me, I've made a script that revive NPC units after a certain amount of time, and if it's more than 25 or 35 seconds, it will simply set their dammage to 0 but not re-animate them. So they just lying there fully healed but do nothing.
Also, if you wanna do reviving in MP, make sure you tell every machine (broadcast publicVariable) that they are revived, else, all the client machines will be seeing corpses floating around the ground and shooting!