When some sensors become power-exhausted in Wireless Sensor Networks (WSNs), mobile redundant sensors might be moved to cover the sensing holes created by the failed sensors. Within rugged terrains where wheeled sensors are unsuitable, other types of mobile sensors, such as hopping sensors, are needed. In this paper, we address the problem of relocating hopping sensors to the detected sensing holes. In fact, the state of these areas - harsh terrains, disaster areas, etc. - may be irregular; however, recent literature only considered movement of hopping sensors within regular areas. Hence, this paper analyzes cases that consider the level of irregularity and the number of hops required. The major contributions of this paper are a definition of the level of regularity of an area and an analysis of the performance of the proposed reliability-based schemes according to total movement and lifetime of sensors. Simulation results show that the proposed schemes outperform the shortest path-based scheme under rugged terrains.