The context was mulled-wine serving--about which we must first have an aside. You don't get it as much at Christmastime in the US--probably because we have our standard Christmas drink, egg nog, instead. But when I moved to the Midwest, home of many Scandinavian-descended peoples, I did come to know it well. And, whenever we served it (back in the days when I was living with a Scandinavian-descended person), we served it in hot drink vessels--coffee mugs or the like. In restaurants, it might be in the kind of glass mug in which you'd be served a caffe latte. But whenever it is served in the UK (in my now-extensive experience of southern English Christmas parties), it is served in wine glasses. Is this a universal difference between the US and the UK, I wonder?
But back to our party: Better Half asked whether anyone would like a top-up (of mulled wine) and the Brooklynite commented (something like): "Now there's a linguistic difference. We'd say refill."
And I thought, "Oh yeah, we would, wouldn't we?" Americans refill drinks, the British top them up. In the UK, the common American experience of (orig. and chiefly AmE) bottomless coffee (i.e. free refills) is not common at all, but in the US, the (AmE, often jocular) waitron will flit from table to table, coffee pot in hand, asking "Can I get you a refill?" or "Can I warm that up for you"? If this were to happen in the UK, it would be most natural to ask if the customer would like a top-up.
But the other common use of top-up these days is what you do to a pay-as-you-go (BrE) mobile/(AmE) cell phone. (The picture is a common site in the windows of (BrE) corner shops and (BrE) petrol/(AmE) gas stations in the UK.) Which led me to wonder: what do Americans say for that? Pay-as-you-go phones are much more common in the UK than in the US, but from what I can gather from the interwebs, refill is used in this context too. Here's a 2004 news release about an American "prepay" phone service:
As always, Verizon Wireless prepay service allows customers to refill their minutes over the phone, at a Verizon Wireless Communications Store, online, as well as at RadioShack, Circuit City and other authorized agents.You could also in the UK use top(-)up for a number of other things that are refreshed by the addition of more of something. For instance, you could get a top-up loan (well, maybe not in the current economic climate), a top-up dose of an(a)esthetic and you can top up your tank with petrol/gas. The phrasal verb top up is only cited from 1937 in the OED, and the noun top-up only from 1967, explaining why it's not as common in AmE. American readers, what would you use in these contexts?