To achieve required sensing coverage for a very long period of time is an important and challenging problem in sensor network design. Recently, Tong et al. have proposed a node replacement and reclamation (NRR) strategy, and designed an adaptive rendezvous-based two-tier scheduling (ARTS) scheme. However, the ARTS scheme only considers point coverage but not area coverage, which is required in many applications. To address this limitation, we propose in this paper a new implementing scheme for the NRR strategy based on a novel staircase-based scheduling model. Extensive simulations have been conducted to verify that the proposed scheme is effective and efficient. Key Words: Sensor Networks, Reclamation and Replacement, Duty-cycle Scheduling.