refill has 2 distinct synonyms spread across 1 of its 3 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a prescription drug that is provided again
“he got a refill of his prescription”
a commercial product that refills a container with its appropriate contents
“he got a refill for his ball-point pen”
Synonyms, antonyms and the broader and narrower relations for refill come from Princeton University’s WordNet. Full sources and licences.
fill something that had previously been emptied
“refill my glass, please”