Unattended Wireless Sensor Networks (UWSNs) are networks that operate without on-line data collection entities (Sink Collectors). This configuration enriches their flexibility but, at the same time, introduces new security issues. A challenging issue is data survival: in absence of the sink, in fact, data sensed by network sensors cannot be kept clear from the adversary. Cryptographic schemes, moreover, cannot be easily implemented: cryptographic material as well as sensed data are continuously exposed to the activity of a smart adversary. Several strategies were proposed in literature which collectively attempt to mitigate this challenge. In this paper we investigate the use of replication as a mean to enhance the survival probability of collected data. We propose a scheme that deterministically grants data survival against a focused mobile adversary. We analyze the behavior of our proposal and study its security and efficiency properties to prove its suitability for UWSNs.