We propose a novel link-based formulation of the WDM network reconfiguration problem for the semi-dynamic scenario, where reconfigurations are required in a series of sessions as traffic demands vary. Each reconfiguration session must consider existing connections obtained from the previous reconfiguration session. We coordinate the reconfiguration of existing connections with the new traffic demands by minimizing the rejected demands and reconfigured connections. With a much more complicated formulation, we are also able to incorporate the fairness consideration. The Lagrangean Relaxation and Subgradient Methods (LRSM) are successfully used to solve the WDM network reconfiguration problem. We demonstrate superior algorithm performance and reduced computation complexity in sample networks. In addition, we demonstrate that there is a benefit of using wavelength converters in WDM network reconfiguration problem, in contrast to the conclusion of the previous studies that wavelength converters are of little value in the static RWA problem.