how to promote a student to another grade level within the current year?

I have this situation
sometimes a student or two need to be moved (promoted, usually) from one level to another but there's no facility, as far as I can tell, that would allow to do this
If I drop the student and then re-enroll the student, I get the student listed twice
there doesn't seem to be a clean way to do this, if there is can someone point it out?