To touch up is to repair your appearance slightly. Touch up the lipstick, touch up before going in.
It is a small correction rather than starting again, which is the whole idea. To touch up paintwork is the same word used of a wall rather than a face.
1phrasetouch upTo repair your appearance slightly.
“She went to touch up before the photographs were taken.”
touch up is a phrase.
Practised in Hair & Grooming