In this paper, we describe an interactive approach to design mobile sensor networks. The node-mobility aspect requires an online or interactive algorithm to determine the optimal network-coverage solution for a given area of interest. Hence, we develop a real-time genetic algorithm to find the suitable direction of node locomotion, considering either coverage of the target area or estimation of the optimum energy consumption. The main purpose is to provide a solution that can extend the network lifetime. The simulation results indicate that the proposed fitness function achieves our objectives.