P2P data stores excel if availability of inserted data items must be guaranteed. Their inherent mechanisms to counter peer pop- ulation dynamics make them suitable for a wide range of application domains. This paper presents and analyzes the split maintenance opera- tion of our P2P data store. The operation aims at reorganizing replication groups in case operation of them becomes sub-optimal. To this end, we present a formal cost model that peers use to compute optimal points when to run performance optimizing maintenance. Finally, we present experimental results that validate our cost model by simulating various network conditions.