Many recent manufacturers in various industries constantly modify or redesign existing products with inserting new technologies to retain their competitiveness. While most of the design research has concentrated on creating new product, few studies have conducted how to redesign the preceding product having its own architecture. This paper proposes a new methodology for re-architecting the modular product with accommodating new required changes is proposed. The proposed method defines re-architecting operators through the use of a design structure matrix (DSM) technique to systemically operate pre-existing modules. Re-architecting strategies and corresponding new architectures are then generated by the combinations of applying the operators to modules. The proposed methodology selects the best one in terms of modularity among the alternative architectures realized with re-architecting strategies. As a result, the best architecture that changes the original system as little as possible and has high modularity is determined through developing algorithms which control the operators.