When you run into someone you haven't seen in a long time, it's common to say, "let's catch up soon." In my experience, this has become an automatic response that has lost its meaning to the point that it effectively means, "I have to go." If you actually intend to catch up, you should pull up your calendar and set a tentative time.
Unfortunately, empty platitudes are everywhere. For example, it's common to greet people with, "how are you?" even when you don't have time to listen to any response other than, "I'm doing well. How about you?"
This year I going to make a concerted effort to minimize my use of empty platitudes. When running into someone, I'm going to start saying, "it's good to see you," instead of, "let's catch up," unless I actually intend to follow through.