I asked this same question on a Facebook Group (Cabana Bay) and apparently they are currently not doing the refillable cups as of a few days ago. Not sure if that will change, but I hope so!
We were just there and I can confirm cup refills via the freestyle machines are working in the parks.Just wanted to add, I called Cabana Bay and they confirmed the refillable cups are still not available and they are not sure when they will be.
I find this a bit strange because I'm almost certain that they are doing refillable mugs in the parks. So if they are working in the park, why not the hotel?
We were just there and I can confirm cup refills via the freestyle machines are working in the parks.
Edited bc i am terrible at phone posts