The person who repeats a story may be returning to a place where they feel known.

Repetition is not always forgetfulness. Some stories are places rather than information, and a person returns to them because that is where they were understood, or useful, or young. Hearing it for the fifth time can feel like a small tax. For the teller, it is often a way of staying near something warm.

You do not have to pretend it is new. You can listen for what the story is protecting and ask a question about that part instead. A small question about the people in it usually opens a conversation neither of you has had.