Cancelation of sale agreement.

I have entered into an agreement for sale of housing property. One of the clause is " after receipt of copies of all documents the buyer will register the sale deed within 90 days". Agreement is not registered.Copies of all documents provided to the buyer. Now the period is over. We waited for another 3 months, as he went on promising registration within fortnight, on many occasions by giving one or the other reasons. Now we have issued him legal notice that if he fails to register within 7 days of receipt of the notice the advance amount of Rs. 10 lakh will be forfeited and agreement cancelled. He replied stating that copies of documents are not supplied to him and asked for copies of documents. On receipt of copies of documents he will register the sale deed with in the stipulated time. We have issued him re-joinder notice denying his stand and reminded him that copies of all documents have been given to him in the month of Jan 2021.But we have taken his acknowledgement when copies given in good faith.Made it clear that all averments are same as made in the earlier notice. My questions are: 1. Can I forfeit the advance amount and cancel the agreement. How should I go about it. 2.Can I go for fresh sale with another buyer? Please let me know the safe option to come out of this deal.