Anmol,

You have to report again to freeze your choice. Generally, if you are opting auto upgradation of college (or stream) and before the 7th round, if you're not freezing your choice, it'll go on upgrading if you're getting something better as per your choice and depending upon the availability. If you're not freezing anything after your first round, then the allotted seat in the first round will be the final one.

Regards