Just had an experience with this. Was staying at BWV on points.
Bottom line, Disney gave me 3 single day park hoppers for my unused days on my current hopper. They are good for 3 years and are not upgradeable. But if you want this possible compensation, you will need to notify the hotel when you test positive and they will shut your current ticket off for the next 5 days.
Detail:
Tested positive on Thursday 8/4. After video discussion with doctor, determined my symptoms started 8/2. Self-isolated in room.
Friday 8/5, had DND on door. Housekeeping called and asked when they could come in. Not sure why as this was not our trash and towel day. Advised I was isolating due to positive Covid test. Was told someone would call me back to check on me later. No call received.
Saturday 8/6, still isolating, Housekeeping calls again, this time it IS our trash and towel day, also said they needed to do visual inspection. Again advised I was isolating due to positive Covid test. Again told someone would call and check on me.
This time I do get a call about an hour later from a manager. She advises me they will be shutting off my ticket access for an additional 5 days (we still had over a week left on trip). I could re-enter park Friday 8/12. This did not sit well with me as it would mean Friday was really day 10 for the purposes of calculating isolation/mask requirements and CDC guidelines stated I could leave isolation on day 6 if symptoms were improving (and they were actually gone by this point). Manager stated they could not start 5 day period until tomorrow because they were just notified. I explained I did notify them Friday of my positive test Thursday. She asked who I told, and I explained about the phone call from Housekeeping the day before. She said nobody told her, I repeated I told them. So now she says I will be shut off until Wednesday. Better, but still not thrilled. She informs me someone will contact me via text with further info and to answer any questions. I asked about my unused ticket days and she said no cash refund, but they will issue tickets for the unused days.
Later that day I get a text advising me my ticket will now be active Tuesday. I did not ask why there was a change, but my guess is they saw I had not been in a park since the prior Wednesday and so counted that as my day 0, which would mean my 5 day isolation requirement per Disney would run through Monday.
I wanted to rearrange a park reservation day and ADR and they took care of that, even though the park we wanted the reservation for on the new day showed no availability.
I was able to use my ticket on Tuesday as promised.
Upon checkout, I had used 6 of my 10 hopper days, and the rest of my family had used 9 of 10. I texted and asked if I needed to stop by the front desk to deal with my unused days and they replied they would take care of it, issuing 4 single day hoppers to me, and 1 to each of the rest of the party, all would show on the App. However, we planned to go to Epcot after checkout so I told her I would only need the 3 days for myself. She said they would show within an hour, and they did. I asked if they were upgradeable and was told no, which makes sense.
So again, bottom line, when it comes to park tickets they do have a policy in place and it is possible to get some replacement tickets. But you will need to notify them of your positive test and have your current ticket shut off for the next 5 days.