Just found this thread while searching and hope this helps someone.
I have a 2014 P85D with 69k CPO. Brought it in 4 times complaining about the battery and finally they took it and admitted that the battery needs to be replaced. They said they don't know if it's another 85kwh or a 90kwh battery until it comes in. Let's pray it's a 90kwh.
I think it is almost certain you will get a 90 - based on what I have read for the P85Ds.
Congrats....I have taken it to Tesla 3 times. My range loss is similar I have a 90d 294 range new...get 249, 45 miles loss in range at 100%, 15% range loss 60k miles. I have filed complaints aginst Tesla on the dca.ca.gov and the new motor vehicle board. They have denied both times. Not sure what else to do???
Like me you need to get range loss "up" - 15% is presumably not enough. Mine is around 12% down so far at 37k miles. Joys of the 90 kWh V1 battery!