void CheckPoint (string& asName, string& asStartPos, string& asCallback, string& asDeathHintCat, string& asDeathHintEntry);
Sets a checkpoint at which the player will respawn in case he dies.
With the checkpoint you can also call a function after the player dies. In that checkpoint function you can for example reset some entities with:
void ResetProp(string& asName);
Resets a prop's state to the original one when the map was loaded.
And you can just use
SetEntityActive("enemy_name", true);
again on the same enemy to spawn it again