The mugs can be refilled at the gift shop and at the pool. Or at the Mara. There are sandwiches at the pool, but the food at the pool is not covered by the meal plan. The only place to eat CS as defined by the meal plan is the Mara.
There are really very few breakfast snacks that can be purchased with the meal plan at the Kidani gift shop. There were some cheap looking prepackaged muffins and danish that could be purchased with snack credits.
Kidani really needs a real counter service restaurant.