Hello Aspirant,

See if you have been allotted a seat then you have to pay the required amount to keep that seat reserved for you and if in next round of CSAB you would be allotted any other upgraded seat then the required amount will be adjusted and you will not required to pay again and again for each round of CSAB counselling.

For complete details about CSAB Counselling kindly check out the link given below :-

https://engineering.careers360.com/articles/csab

However I would recommend you to use JEE-Main College Predictor to predict the chances of your admission in different colleges  based upon your percentile and category :-

https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

I hope this information helps you.

Good Luck!!