Scorpions do not normally regenerate lost limbs. It's spiders that have the ability to completely restore lost limbs over a few molts. Regeneration of lost limbs within scorpions is either super rare (hasn't been confirmed) or does not exist altogether. There have been experiments done with scorpions quite cruelly and there is no evidence of a scorpion fully regenerating a complete lost limb. It is said that scorpions can willingly detach their tail along with the telson but they do not survive long as the anus of scorpions is close to the telson and they die within a couple of months. Partially regenerated limbs have been reported but not to the extent of the scorpion being "whole" again. In other words, they have been reported to regrow one segment of an individual limb, never the whole thing. However, there is far more evidence of regrowth of the aculeus (actual stinging pointy bit) where it has been damaged or snapped. Regrowth evidence are far more substantial in that area although it does not regenerate or grow to original size.