I think the problem you’re running into is that the Regeneration function is being called each frame for 10 seconds before health reaches over 100.
You can use the return command to exit a function (to answer your question), but I think re-ordering your script might be the solution. (I know I’m assuming a lot.)
Add a regeneration boolean.
var regenerate : bool = false;
Check for the bool to start regenerating only once.