top up

verb (transitive, adverb) (Brit)
1.
to raise the level of (a liquid, powder, etc) in (a container), usually bringing it to the brim of the container: top up the sugar in those bowls
2.
  1. to increase the benefits from (an insurance scheme), esp to increase a pension when a salary rise enables higher premiums to be paid
  2. to add money to (a loan, bank account, etc) in order to keep it at a constant or acceptable level
noun
3.
  1. an amount added to something in order to raise it to or maintain it at a desired level
  2. (as modifier): a top-up loan, a top-up policy