Through the numerical calculations we show that the performance of the femtosecond filament and plasma channel in a Kerr medium can be made better than that of a single Gaussian incident beam if superposed Gaussian beam composed by different beam radii while keeping total pulse energy entering the Kerr medium.This can be interpreted as an active use of the energy reservoir effect in a sense that the energy pooled in the wing of the spatially broader Gaussian beam provides energy into the core of the superposed beam to maintain the filament for a longer distance.