*top (something) up*
Definition: to re-fill a glass or cup when it still contains some liquid.
E.g.1: I didn’t like the wine so I only drank half of it. Unfortunately, the host topped the glass up so I had to drink some more.
E.g.2: In some cafes the waitress will keep topping your coffee cup up until you don’t want any more, but you only pay for one cup.
This phrasal verb can be separated. (E.g. 1 and 2)