Kinetic energy $K \propto 1/\lambda^2$. If the wavelength is halved, the kinetic energy becomes $1/(1/2)^2 = 4$ times the initial energy ($K_2 = 4K_1$). The energy added is $K_2 - K_1 = 4K_1 - K_1 = 3K_1$, which is thrice the initial energy.