Let's do this again

Let's do this again (sometime).

 and We must do this again (sometime).
an expression indicating that one member of a group or pair has enjoyed doing something and would like to do it again. Bill: What a nice evening. Mary: Yes, let's do this again sometime. Bill: Bye. Mary: Bye, Bill. Sue (saying good night): So nice to see both of you. Mary: Oh, yes. We must do this again sometime.
See also: again, this