@ Sumit
I am assuming you got the RTR license after passing both part 1 and part 2
So inorder to renew it you need to pass part 1 only . After you pass part 1 you can pay the 10,000 rupees DD and get it renewed for lifetime
I know this method applies to those licenses before it expires . I am not sure if it applies after it expires....
Try contacting an RLO or visit your nearest RLO and ask them directly