See as per the information available on the KVPY website, the student eligible for the SB stream is that the candidate must be enrolled in the 1st year of an undergraduate program in Basic Sciences during 2021-22. So you are eligible for the examination as there are no other condition provided.

To know more about KVPY eligibility criteria visit the link below:

https://school.careers360.com/articles/kvpy-eligibility-criteria

I hope this answer helps. All the very best for your future endeavors!