Land Agreement Expired -- Implications

Father - Durga Murthy, had an agreement with purchaser to sell the land for 10L and has signed an agreement of sale in which it was mentioned that purchaser would get the land registered within 3 months of the agreement and paid a token amount of 50000, clause of cancellation was not in the agreement. Post agreement , he got the diversion done and also invested to get the land leveled and put a board to sell the diverted land without our permission. Once amount was not paid within 3 months, we sent a notice to cancel the agreement within 1 month post expiry, purchaser replied saying that he is not buying because demarcation is not done.. now it is already 2 months over since the agreement cancellation and there is no intent from purchaser to buy the land. In the notice for cancellation, we mentioned that we would payback the token amount and also amount for diversion,, if he is not able to buy the land as we cannot wait for long.. but purchaser is just passing time.. Please advise what can be done in this case...