The phrase "a refill of coffee" is correct and usable in written English.
You can use it whenever you want to refer to getting more coffee after already having had some. Example: "I'll have a refill of coffee, please. I have a long day ahead and could use the extra caffeine."
I'm still looking for that one free refill of coffee with a picture of Rembrandt on the napkin".
Finally, I take a swallow and another, and get a refill of the Lamberhurst Estate Fume.
The regulars at Moore's Cafe are holding court at the counter, nursing refills of coffee.
Even as Starbucks branches have cropped up nearby, and similar coffee shops have become overrun with laptop users, the Hungarian Pastry Shop has kept an Old World style by remaining cash only, dimly lighted and offering no Wi-Fi or electrical outlets, even while offering free self-serve refills of coffee.
Furthermore, when we asked for a refill on the coffee, the waiter refilled everyone's coffee at the neighboring table and forgot to refill ours, and we heard people at a table close by get a random order of bacon (maybe I would have a different view of the restaurant if I had gotten a random order of bacon as well, but obviously accuracy is not really a high priority at Panificio).
When it's just your laptop, it's not so bad — get a refill on that coffee!
In fact, this Continental breakfast was almost too generous: a gigantic fruit plate, a big bowl of granola with yogurt and fruit, an assortment of pastries, a large custom-blended fruit drink (pineapple, orange and ginger was a favorite) and ample refills of excellent coffee.
Electric cars will become commonplace once there is a dense network of high-voltage charging stations where drivers can refill their batteries in the time it takes to use the restroom and drink a cup of coffee.
