When one dreams of the past there is a level of longing or even being stuck in an energy which no longer exists, but still needs to either be healed or purged from the mind of the dreamer.

This can only be done is the same story is repeated over and over again in order to accept it and move on. Perhaps in the dream you have a reoccurring event that happened in the past? This is obviously coming to revisit you in your subconscious mind. It is important to understand to never shrink away from the responsibilities of the past, try to become consciously aware of these past events which will makes it easier to purge.