Regarding growing back...
When my youngest had her first surgery, we asked the doctor to remove the smaller hemangioma on top of her head (in addition to the larger one on the face, just below the eye). The one on top of her head had always been the less aggressive one, and responded well to the steroids. It never got bigger than about an inch in diameter, and protruded about 1/2 inch.
Doctor said that the scar on top of the head would be raised for a few months, then flatten out - which it did. Then 3 or 4 months after the surgery, it started to "come back." It is still a little puffy and red even now, at 3.5 years old.
Since it is under hair, you don't usually notice it (though her hair is not real thick, and it is blond). Even more interesting I think - and it may be an "illusion" of sorts - is when you feel that area on top of her head, you cannot feel the skull. Feels like a depression there, wonder if we should have done the CAT scan as recommended in the MRI report (as they could not tell if the top of head hemangioma might be going into bone).
I would follow the wait and see, or if you are really concerned, find someone willing to do steroids. Long term effects have been studied - perhaps you can contact one of the experts on this site. I don't know why you would need sedation for laser of a fairly small area. I know some doctors will do sedation or GA for some procedures, and others will not do anything. My youngest had no sedation for the steroid injection into the face, just below the eye.
Good luck, try to enjoy your new addition, don't worry too much about the hemangioma.