The search efficiency improvement especially concerning search for rare files is a fundamental challenge in mobile peer-to-peer (MP2P) systems. In this paper, we propose a simple and efficient replication technique to increase file availability in MP2P systems which enhances the search efficiency. The aim of our proposal is to maintain a threshold level of availability at all times in order to find a file within a small number of overlay hops even for rare file. We base on a global availability estimation to choose suitable file to replicate and suitable replica degree. Simulations show that our proposal significantly improves search efficiency in terms of search success, search delay and overhead.