There's no such native option, in the current version, but it's super easy to script. We can leverage the takedamage event since it activates right after the entity has damage applied to it but before the death logic takes place.
All you need to do is create a script file and reference it in the model text file header like this:
Code:
takedamagescript {path to your script file}
Each time an entity with that model takes damage, it will execute the script file in {path}. I wrote you an example of what the script file itself looks like. You can
view it here. All it does is look at the entity's current hitpoints and restore them to 1 if they are at or below 0.
HTH,
DC