Hii inchara!

You are on the right path as your OBC NCL certificate issued in February 2025 will not be accepted as per the latest JEE guidelines. The most practical step would be to immediately apply for a fresh certificate from your nearest issuing authority which will naturally take around 15 days minimum to 1 month maximum ( you can request them to issue your certificate on priority basis).

Secondly it's obvious that a new certificate would have a new RD number and that is completely acceptable.

In case your new certificate is not ready by the time counselling or document verification starts you can still apply for it by submitting a official declaration form which is provided on the official JEE advanced website. You can upload it in the place of certificate and later upload the valid OBC NCL certificate which is issued after 1 April,2025 once you receive it.

This ensures that you do not lose your category benefits during the process.

Hope it helps!