Reopening of a case after dismissal.

My grandfather's pr8operty in Tamilnadu was inherited by my father. My father gave the land on lease to a person who subsequently abandoned it leaving it vacant.My father died young and was not aware of the same. Many years later we came to know that the subject land had been classified as poramboke in the revenue records and taken over by the govt. We went to court claiming ryotwari patta and our plea was dismissed on the basis of limitation prescribed by a G.O.714 of 1987. This G.O. is only applicable to revisions and appeals in earlier rejected cases and not in original applications as in our case. This point was ignored by the High Court and we did not have the sale document or the lease deed at that point of time to establish our claim. We could find the same only 3 yrs after the dismìssal by court. With this new evidence how do we proceed. Do we go to the Revenue dept or Civil court or can the case be reopened in the High court? Our lawyer says once dismissed its final.This property of 50 acres is very valuable now as the area is well developed. Kindly advice.