Hi Leanne,
My axololts are heavy breeders, too. They lay eggs every three weeks. They started in April and haven't stopped yet. I believe that some strains of axolotls are simply prolific breeders; considering that their ancestors were lab specimens, this makes sense to me.
Fortunately my female is fully adult and quite robust; nevertheless, I will be separating the two permanently soon. It is a lot of hard work for her to create so many eggs so often.
-Eva