From Longman Dictionary of Contemporary Englishtop something/somebody ↔ up phrasal verb especially British English1 FULLto add more liquid to a container that is partly full I’ll just top up the coffee pot.2 DFDPOURto put more drink in someone’s glass or cup after they have drunk some Can I top you up?3 INCREASE IN ACTIVITY, FEELINGS ETCto increase the level of something slightly so as to bring it back to the level you want He had to do extra jobs at the weekend to top up his income. → top-up → top→ See Verb table
Examples from the Corpus
top up• The eggplant on top was curled up.• On the eighteenth day a cloudy mountain top arose up across the sea.• Here the bamboos of the top layer jostled up and down against one another as each wave rolled underneath them.• Instead he found a thin glass and poured what was in the mug into it and topped it up from the pumps.• Most often, the top covers up its bind in the name of keeping up good relationships.• They can stop paying into their company top - up plans, but there is little point in calling Equitable for advice.• Results claim to last 12 - 18 months - a top - up treatment is included in the course, it necessary.• The top end finishes up with the three-over-two layout of Gotoh black chrome machines.top-upˈtop-up noun [countable] British English 1 DFDPOURan amount of liquid that you add to a glass, cup etc in order to make it full again Would you like a top-up?2 an extra payment that brings an amount to the desired level top-up loans for studentsExamples from the Corpus
top-up• Automatic top-up with a ballcock will allow all water in a new pool to pass first through the Eradicator.• Because of its size it is able to keep companies on its books for 20 years or more, providing top-ups when necessary.• The awards will take the form of a salary top-up for a maximum period of five years.• Factoring finance sometimes provides the top-up needed to make a buyout possible.• They see sponsorship as a useful top-up.From Longman Business Dictionarytop something → up phrasal verb [transitive] British English to add to something in order to bring it up to the level you wantYou can top up your pension contributions any time. → see also top-up → top→ See Verb tabletop-upˈtop-up noun [countable] British EnglishFINANCE an extra amount added to something in order to bring it up to the level you wantYour bank may agree to provide the top-up needed to make a purchase possible. —top-up adjective [only before a noun]a top-up loantop-up fees 