Hello, 

No the seat choice filling is done only once before the 1st round of counselling. If you are not able to get a seat in round 1 then wait for further rounds . If your rank comes in the merit list of colleges you have filled at the seat locking time, then you may get it and there is a probability that you do not get any seat in upadesh if you have filled only soms colleges and tour rank does not satisfies the cutoffs of that college.

All the best!!!