Hello,

You haven't mentioned the name of the exam for which you wish to know. So I am providing you wish a general idea:

During allotment of seats during counselling, there is an option that lets you confirm the college that you have been allotted but at the same time go for upgradation. This is called "accept with upgradation". For this, you will need to pay the admission fees of the colleges that you have been allotted and at the same time have the option to upgrade to colleges higher up in your preference list. For example, if you got a college that was placed 8 in your list, you can confirm and upgrade to colleges between 1-7 in your list.

Hope this helps you.
All the best!