To talk without any special target is good, but I feel that at the end, the topics are the same, and the conversations are similar.
I have read that another way of making language exchanges is with rol games. Have you ever tried? Is really more efective than normal talking? Do you know another way?
(Please, feel free to correct my mistakes)
PS: The following Role Play Topics are just a small sample from the game, Roll Play, by Dymon Publications.
A: Invite B to go somewhere this weekend. B: Politely refuse A's invitation.