make twice as great or intense; "The screaming redoubled" double again; "The noise doubled and redoubled" double in magnitude, extent, or intensity; "The enemy redoubled their screaming on the radio
If you redouble your efforts, you try much harder to achieve something. If something redoubles, it increases in volume or intensity. The president also called on nations to redouble their efforts to negotiate an international trade agreement The applause redoubled. redouble your efforts to greatly increase your effort as you try to do something