In this paper, two efficient redeployment strategies which are designed to balance the detection coverage rate and maintenance period are proposed. To develop these strategies, we first analyze the sensor detection coverage and energy consumption model. We then propose a network maintenance indicator that considers the coverage rate and residual energy in each node. We adopt the network maintenance indicator as the cost function. That is, the network maintenance is formulated as a cost optimization problem. Finally we propose COST_MAX_MIN and COST_MAX_AVG strategies to select the redeployed location of candidate nodes. Simulation results show that the COST_MAX_AVG prolong the repair period in comparison with the COST_MAX_MIN strategy.