To liven up is to make something more interesting or cheerful. Liven up the room.
It works both ways, so a party can liven up on its own or somebody can liven up a party. To liven up a dull talk usually means one good story rather than more slides.
1phraseliven upTo make something more interesting or cheerful.
“A few plants would liven up the whole office.”
liven up is a phrase.
Practised in Phrasal Verbs