It means that she is looking for some type of closure by attempting to succeed this time She failed last time, and she won't feel right until she succeeds.

This is a scenario of post-trauma healing. We are in the realm of psychotherapy. "To lay the ghost of something to rest" is to finally stop being worried or upset by something that has worried or upset you for a long time". To have been nearly killed is obviously a very traumatic experience. It is conceivable that she is suffering from post-trauma issues. "To revisit" in this context is to talk about or go over the incident with a therapist, the people involved, or others, as part of a healing process. It does not necessarily mean she needs to try to break the world record again until she succeeds. "We've ghosts to lay to rest" means she has not got over it yet, and needs to deal with psychological issues arising from the incident.

To put to rest something that has been bothering you; to face a past fear or failure. Another expression that is similar: "facing your demons of the past." "Closure" is a good word for it.