top-up

Short definition from Wiktionary

Adjective

1. 1
   That serves as an addition

Noun

1. 1
   An addition.
2. 2
   A serving of drink used to top up an existing glass.
3. 3
   An additional premium paid over the initial premium in order to increase benefit values.
4. 4
   Additional credit purchased for a mobile phone.
5. 5
   A dose of epidural anesthetic added to previously injected spinal anesthetic in combined spinal-epidural anesthesia
6. 6
   The situation where a student who holds a qualification equivalent to part of a degree course is then accepted onto a degree course at an intermediate point, without having to start it from the beginning.

Verb

1. 1
   To refill (or recharge) something.
2. 2
   To refill (or recharge) something: To add to a balance in an account (e.g., mobile payment, debit card, bank account).
3. 3
   To refill (or recharge) something: To refill a drink.
4. 4
   To refill (or recharge) something: To add to a number or amount, to bring something up to a certain level.
5. 5
   To have sex (with).