From what I have gathered, in order to renew the RTR I need to submit the following documents.
1) Photocopy of Logbook showing 30 hours of flying during the preceding 36 months. This is counted from the date of expiry of your Indian RTR backwards. Copy of first page of Logbook showing your name also reqd
If you dont have the 30 hours, you need to give Part 1 of the exam here in India.
2) Copy of your RTR issued by WPC New Delhi
3) Your foreign CPL along with Medical cert
4) Fill out application form 23 COP (good for it) and attach 2 passport size photographs.
5) Bank Draft drawn in favour of PAO(HQ), DOT, New Delhi for RS, 5000/- from STATE BANK OF INDIA only
Have these documents attested by a Gazetted Officer or Justice of the Peace.
Send these in a sealed envelope to the address in New Delhi which is mentioned on the COP 23 form, on top.