We were looking for the same thing on our trip this last Jan.
My Mom was craving some carrot juice and I was at a loss. Wonders of Life at Epcot was my first thought but it is closed "seasonally" right now.
I know they used to have fresh squeezed OJ at a couple of resturaunts (Pepper Market, etc.) but I don't know if they still do and thats fruit juice.
Good luck. I hope you find something we missed.