Hi,
My Bertie had really bad neuropathy when he was diagnosed. But he recovered completely.
Nerves do heal slowly though. So it can take a wee while to see progress.
Are you giving methyl B12/methylcobalamin? Many of us have found that it can really help.
Also, in some cats, leg weakness can be caused by (or exacerbated by) potassium deficiency. (If a cat is peeing a lot they can excrete too much potassium from the system).
Here's hoping your kitty feels much better soon.
Eliz