8 Weeks Ago, I Had a Gum Graft Done and Still Have No Feeling in my Lip or Chin?

what you are experiencing is called Dysthesia.  It is parasthesia that is associated with pain (partial loss of sensation with spontaneous pain).

In the case of parasthesia (numbness), Usually a steroid med, high doses of NSAIDS are prescribed, the patient is followed up every 2 weeks, a sensory test is performed (mapping the area of altered sensation with a sharp instrument , we map the size of the area).  This is done every 2 weeks, to see if the area gets any smaller in size, if the sensation comes back. 

Hypercium , Vit B (Thiamine) might be helpful for nerve regeneration (right after surgery, but controversial ) .          

In your case as you have mentioned, Dysthesia has been  the result of direct trauma to the nerve (the surgeon cut the nerve?). 

If you are sure that the nerve was cut,  you will need a referral to someone that is trained in nerve repair.  The sooner this is done, the better the outcome.   

wish you all the best