With the growth of computing power and the proliferation of broadband access to the Internet, the use of media streaming has become widely diffused. By using the P2P communication architecture, media streaming can be expected to smoothly react to changes in network conditions and user demands for media streams. To achieve continuous and scalable media streaming, we proposed scalable media search and retrieval methods in our previous work. However, through several simulation experiments, we have shown that an LRU (Least Recently Used) cache replacement algorithm cannot provide users with continuous media play-out for unpopular media streams. In this paper, inspired by biological systems, we propose a new algorithm that considers the balance between supply and demand for media streams. Through several simulation experiments, it has been shown that our proposed algorithm could improve the completeness of media play-out compared with LRU.