From Longman Dictionary of Contemporary Englishpolish something ↔ up phrasal verb1 (also polish up on something)IMPROVE to improve a skill or an ability by practising it You should polish up your Spanish before you go to Chile.2 to make something seem better or more attractive to other people The company needs to polish up its image.3 CLEANto polish something → polish→ See Verb table
Examples from the Corpus
polish up• Henry had polished it up and found the special marks on it. 