Unless something has changed in the last year, there are no self fill stations at bwv. You have to take your mug to the bakery, sweet/ice cream shop, pool bar or lounge and ask them to fill it. Some of those locations will fill the mug and some will just hand you a filled disposable cup.
I know akl has a mug station in the food court, but don't know if/where any of the others are there.