Laser-ablation laser-induced breakdown spectroscopy (LA-LIBS) based on single Nd:YAG laser is used to analyze copper impurity in silver jewellery with enhanced sensitivity and minimal sample ablation. 6-30 folds signal enhancement can be achieved under the re-excitation of the breakdown laser and the spatial resolution is only determined by the ablation laser. 50 ppm limit of detection of copper is achieved when the crater diameter is 17.2 \mu m under current experimental condition. This technique gives higher analysis sensitivity under the same sample ablation in comparison with single pulse (SP) LIBS. It is useful for high sensitive element microanalysis of precious samples.