Top-up = recarga (completar o valor)
to fill something again, after it has been partly emptied. (British English)
- Would you like me to top your glass up with wine?
- If your bath water has gone cold, let some water out then top it up with hot water.
Quem já esteve em Londres sabe que precisa "top up the Oyster Card (Used on the Tube, trams, buses, DLR, London Overground and some National Rail services in London). Auto top-up ensures you never run out of pay as you go credit by automatically topping up your Oyster card whenever your balance falls below £5. You’ll never have to queue to top up your Oyster card again."