Under the provision of migration, a student can migrate from first year to second year of other college under the same University. The subject combinations can't be changed. The College accepts the migration only when there are seats available. After the results are published there are notifications released for application of migration. You need to apply for that. Then, you need to have a good score in the subject in which you want to migrate. You need to get NOCs from the principals of both the colleges. When the procedure completes, you can migrate.
Hope this helps.