If stem cell research was legalized to allow its fullest potential, could there be a possibility of repairing missing limbs?

Not the way that people think it would. Such a technology would still be on par with technologies that would assemble tissues very quickly by mechanical means, just much slower and still requiring a great deal of mechanical interference. It is my opinion that the technology will not allow the limb to be grown directly on the host. Layer by layer a limb might be able to be grown as a grafting process in vitro, and then surgically attached after. This technology is more about fixing damaged tissues than it is about replacing complex organs or appendages. Stems cells could be used to culture the bio mass necessary for future application via alternate technologies.