The paper describes multicriteria modular approach to redesign/improvement of a networked system (e.g., sensor/ actuator network, communication network). Generally, the approach consists of the following stages: (1) revelation of system bottlenecks, (2) generation of alternative improvement actions for each system bottleneck (i.e., new communication facilities as design alternatives for the upgrade process), (3) multicriteria assessment of the improvement actions, (4) multicriteria ranking of the improvement actions, and (5) forming a generalized improvement plan while taking into account a total resource constraint (multiple choice knapsack problem). A set of requirements/criteria is divided into several groups (criteria clusters: reliability, performance, manageability, etc.). An outranking technique (version of Electre method) is used for multicriteria ranking. A multistage heuristic is used for solving multiple choice knapsack problem. A numerical illustrative example of a real-world cooperative communication network is used to describe the suggested redesign approach. Three redesign schemes are analyzed: (1) a new full system design, (2) a partial system redesign, and (3) a hybrid redesign framework.