Your UGC NET JRF certificate under the EWS category should still be valid for applying to PhD programs in the General category, even though you cannot obtain a new EWS certificate due to exceeding the income slab.

The primary purpose of the NET JRF exam is to assess your eligibility for research fellowship and assistant professorship. The category under which you appeared (EWS) should not affect the validity of your qualification itself.

The UGC NET JRF certificate issued by the NTA recognizes you as having qualified for the exam. This qualification is independent of the EWS category you used during application.

https://competition.careers360.com/exams/csir-ugc-net

I hope it helps!