Hello aspirant,

YES, you can give the improvement exams after class 12th, this year, and can improve your score  and overall percentage and can make yourself eligible for JEE mains 2023 examinations.

Further, the JEE mains Eligibility criteria is as follows :

There is no age limit . Candidates must have passed 10+2 or equivalent examinations from a recognised board. Candidates who have passed 10+2 or equivalent examination in 2021, 2022 or are appearing for it in 2021 will only be eligible for JEE Main 2023.

Since you are a JEE aspirant, here are some best preparation tips that I would like to give to you to score a good marks in JEE mains exam :

Prepare A Well-laid Plan

Draft a daily schedule.

Prioritize the topics that require more time and relevant to the subject.

Stick to the routine and pay special attention to problems.

Get Hold Of The Syllabus

Manage your time effectively

Understand Basic Concepts

Before delving into JEE preparations, know the JEE syllabus and understand the basic concepts present in the syllabus.

Evaluate your knowledge on basic concepts.

Make notes on required topics.

Choose The Right Study Material

Further, to know more about the JEE mains Exams in full details, you can follow the below mentioned link to know more : https://engineering.careers360.com/articles/jee-main-2023#:~:text=JEE%20Main%20Eligibility%20Criteria%202023&text=There%20is%20no%20age%20limit.&text=Candidates%20must%20have%20passed%2010,examinations%20from%20a%20recognised%20board.&text=Candidates%20who%20have%20passed%2010,eligible%20for%20JEE%20Main%202023.

I hope that this will help.