Nous reviendrons.
Here's a breakdown:
* Nous - We
* reviendrons - future tense of "revenir" (to return)
You can also use on reviendra which is a more informal way of saying it, literally meaning "one will return."
Here are some other variations depending on the context:
* On se retrouve: We'll meet again (literally: "We find ourselves again")
* On se revoit: We'll see each other again
* À bientôt: See you soon
* À plus tard: See you later