Hello Garv

It all depends on your rank that if the college can be changed or not. Since you have got the college you don't want, you need to further go for the float option. In this way, if any of the seat is vacant in the options filled by you above NIT Bhopal and it is feasible for you to get that on the basis of your rank, then that seat will be provided to you. Please check the order list that you have filled along with the previous year cut offs for the same college. This is the only way that your seat can be changed. You cannot get Mesra again since it is below NIT Bhopal in the list.  

I hope this helps. Feel free to ask any other queries.