I do not have any direct experience in the matter so I can only comment on theory but as no one answered this I will try to at least start a convo for you. It is my thought that because some of it has been changed due to heat, maybe not much of it but some of it, it will at the very least be less potent. Again as I have no experience I can not say with any certainty so if you were going to do it I would not do more because I said it may be weaker.
If you were smoking it prior why do you feel the need to use a different RoA on the left overs in a sense? It would seem if you were unsure of it and you wanted to do meth again, why not smoke it because you know that worked before? Just curious if this is for future knowledge, like you want to start doing this because its easier or you dont have a pipe, or your just trying it for a one time go. I would be cautious about putting burned things in my nose, carbon byproducts arent usually water soluble so it may be damaging.
I hope it helps a little.