Hi Akhilesh!

Increasing your score within few days purely depends on your potential and dedication! By attending the first session exam, you would come with an idea about the pattern and question types. You will be able to know your strengths and weaknesses from the first attempt. From it, focus where you have to work more for improvement. Then work on those topics within those few days. This might help you to some extent!

Hope this is helpful!

All the best!

Nothing is impossible. But you should focus more on the topics and it details. Increase the required rate of problems you solve and focus on the topics as much as you can.

15 days can be a little hard but if you are focused on your syllabus then you will see some positive results.

You should visit the link to know about JEE MAINS 2021 important topics:

https://engineering.careers360.com/articles/most-important-chapters-of-jee-main

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