Ultrafast laser irradiation of planar Au nanoparticle arrays is shown to double the particle plasmon quality factor and to enhance second harmonic generation 40-fold. It is found that the irradiation induces a morphological change of nano-cylinders into asymmetric droplet-like shapes with reduced surface roughness without altering their lithographically defined locations. These findings can be used to improve the performance of linear and nonlinear plasmonic devices.