I have passed my 1st year of B.Tech recently with 80%. Can I write improvements for it to increase my percentage?

HiSneha, 80% is a good percentage and there is no provision to reappear in exams unless you have backlogs and there is no point in wasting one year, if you want to increase your percentage then you can secure better marks in the next semesters to increase the overall percentage of your B.Tech.