Hey Harsh, the application form for Jee advance is filled separately and has not been a part of Jee mains application form since the last few years.

If nothing is changed by the NTA then you will have to apply for Advance separately and there you can change your category to be as EWS.

But make sure that you verify your category and other claims as failing to do so can lead to instant rejection.

Hope this helps.

For more query regarding this please ask in comments.