Hello aspirant, first of all congratulation son getting a rank of 2494 in VITEEE and getting a category 2 seat. As far as I know you have only 2 choices. Either you can forfeit the seat or you have to book it. So it won't be possible to upgrade to category 1 once you have got the seat in category 2. You should book the seat if you are comfortable with the fees of category 2. The tuition fee for category 2 is around 3LPA. For further information about counselling process visit -

VITEEE Counselling 2021 (June 21)- Dates (Released), Registration, Schedule, Procedure (careers360.com)

BEST OF LUCK!!