This is one of the most common questions asked by students in their first year at RGPV. Most of these students are admitted based on the score obtained in the CLC round. Due to this, they are only left with 2-3 options(Mechanical or Petrochemical) to avail seats.
It would not be possible for you to upgrade the branch assigned to you during enrollment. If you have a good academic record, the seats are still offered on the basis of vacancy.
For instance, if a certain branch has a seat available for an OBC candidate, then a General category student cannot apply for it. If in any case, none of the OBC candidates applied for the seat only then you can have a chance.
Even if you have a higher score and have no backlogs, in comparison with an OBC candidate having few backlogs, the seat would still get allocated to him.