Yes dear Niyati you can improve your 12th score as per the guif=dlines of CBSE board and the improved score is valid for jee mains or advance totally. Work hard and try to get higher marks in improvement that really help you in future. I hope you do better in your improvement exam.

All the best dear 

Dear Niyati 

yes your score is differnately valid for JEE MAINS 2019 . don't pnic you scored very good in JEE  MAINS 2019 and you can get TOP NIT's but I request you to give JEE ADVANCED 2019 I think you can score well there and can get good IIT.

I wish all the very best for your exam and hope this will help you if not you can comment below 

Thank You !!