I didn’t answer this before because I tot Marcia knew more about this then me.
I don’t think they regenerate horns, however I am not sure?

On a evolution point of view, if these horns are a display (attract females or intimidation) feature, then theirs no is real benefit for them to regenerate.

However should they be an adaptation against predatory, then re-growth should be meaningful.

I think they are ornamental.

Weight is insignificant, it doesn’t mean a thing. I have never weighted any reptiles or eggs in 30 years. I don’t see any reasons? But I am curious as to why you want to weight them? Maybe I am missing something.