Yes, you can change your branch after the first year. IIIT Raipur has such provision for students. 

• In IIIT Raipur there are two branches CSE and ECE and a changing branch from CSE to ECE is easy and common. 
• Most of the students change their branch from CSE to ECE. There are four-five seats in CSE and six-seven seats more likely vacant.
• You can change your branch before the beginning of the 3rd semester. 
• The process of branch change allotments based on the merit list. If you have a high CGPA then you will get preference. 
• The number of seats also depends on the available seats, from the previous year's admission and students who left the seat. 

Therefore, you need not worry about branch change. Because many students change their branch after the first year. Its process is also easy, but branch allotment solely depends on the number of vacant seats and your CGPA.