Hello..!!

Yes, you can fill choices again in Uttar Pradesh State Entrance Exam (UPSEE). 

For more information about this:https://engineering.careers360.com/articles/upsee-counselling

You will have to fill choices according to your rank and your preference of colleges.

On the basis of merit list and availability of seats and obviously your choices, you will get seat in subsequent rounds.

Hope this is helpful.