There are lot of chances are that your rank should be increses. Due to covid 19 many students nit want to give jee main paper 2. Number of students decrease so chances to improve the rank are more in comparison to January exam if you score more percentile in September exam then definitely your rank improve.

Here I recommend you jee main paper 2 college predictor tool which definitely help you.

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

Hope it helps.

Good luck!