Hi aspirant,

You have not mention any colleges so it would not be possible to answer specifically but I can answer you in general about how branch upgrade happens. Around the end of 1st year you would get a notification from your respective college about the branch migration facility you need to fill that form and pay the required fee. Now the academic performance of every candidate would be taken into the consideration and top 1 or 2% candidates are moved to the higher preferred branches. Please note that this facility is not available in each and every college so you would need to confirm it with yours.

Hope it helps!