Thats not very long... its possible it wasnt in the greatest shape when you got it.
They do tend to molt shortly after arriving in a new habitat. I think it might have something to do with the stress of moving. If that was its first molt while in your care, I would suspect that there was something wrong from the start.
That said, if you decide to replace it, then I would suggest doing some research ahead of time. They're a little bit more difficult to care for than fish and shrimp. Having had one, Im not in a big rush to get another.
Check out the Mexican Dwarf Crayfish. While they still have more strict water and food requirements, Ive found them to be a little easier to care for.