Hello dear,this type of doubts are generally happened while counselling.I want to inform that you can use float option which means that you want to confirm the seat presently allotted to you and also at the same time wants to be considered for up gradation of seat in later round of counseling on the basis of your already filled choices.There are two more options available like FREEZE and withdrawal which are not suitable for you.

For your condition,you should use float option.

For complete details like date for FREEZE,FLOAT

Check https://engineering.careers360.com/articles/upsee-counselling

Thanks.