"じゃまた" "またあした" "またね" And the "ne" works at the end of either of the first two.
"Ja mata" "mata ashita" "mata ne"
I'm not too sure about a formal setting. Though, またあした would be the most formal of the three.
It translates to "again tomorrow?" じゃまた to "well then, again?" and またね "Again, right?"