redouble

Short definition from Wiktionary

Verb

1. 1
   To double, especially to double again; to increase considerably; to multiply; to intensify.
2. 2
   To double an opponent's doubling bid.
3. 3
   To become twice as big.
4. 4
   To double again what was reduced to a single state.

Noun

1. 1
   An optional bid made by the side currently holding the highest bid for the contract, after the opposing side has doubled.