At most resorts, no, because there are convenient refill stations. I believe the only two locations at BW to get a refill for the resort refillable mugs are the Boardwalk Deli and the pool bar, but you do have to ask the bartender to refill the mug at the pool bar. I can understand how that's awkward - if you're at the pool over several hours asking for multiple refills, one might feel compelled to tip, especially if they're busy filing orders from people paying for drinks/food who likely will be tipping. And, most people buy the resort refillable mug specifically to get endless free refills during their stay, so if you feel like you need to tip, maybe it doesn't feel worth it anymore.