The rising usage of cellular networks for various devices and applications increases the requirements for the availability and reliability of those networks. Yet, a failure of components on the data path inevitably leads to connectivity loss for users. The standardized restoration procedures after failures, as well as mechanisms for session continuity or redundancy on the data path either have a significant overhead in the control plane or duplicate the entire user traffic.In this paper, we propose a resource-efficient session management mechanism that proactively mirrors the session states of the central core function on the data path, the User Plane Function (UPF), to another instance. Our design is agnostic to UPF and gNB realizations and transparent to the user devices. Following a UPF failure detection, we redirect data plane traffic to the redundant UPF. Additionally, proactive user session mirroring reduces recovery times for the user plane of 5G and beyond. We demonstrate the feasibility of the proposed design with a prototypical implementation, and our experimental results emphasize its scalability and performance.