“Good night.” / “Same time, same place?”
Good night. is used when parting at night, whereas Good evening. greets someone on arrival. Same time, same place? checks a familiar meeting arrangement and becomes a recurring phrase through the end of A1.
“I love that we always say that.”
In I love that …, the first that introduces the fact the speaker loves: we always say that. The final that is a pronoun referring to their familiar phrase Same time, same place?
“small promises” / “keep a promise”
Small promises are little promises; here, the everyday promise to meet tomorrow at the usual time and place. Keep a promise means to do what you promised. They in They are easy to keep. refers to those small promises: they are easy to keep. At the end, Frank repeats Same time, same place. to confirm that they will meet tomorrow too.