Hey there

Yes! you can change you options after the mock seat allotment. The reason for the mock seat allotment process is to give the student an idea about the seat he/she might get as per his or her current college list. If you are not satisfied with the mock seat allotment, you should change the order in which you have submitted your preferences. However in mock round the seats you get are not assured to you because many students tend to change their seats after the mock round.

All the best