  Plasma wakefield acceleration using an electron filament offers stable,
high-gradient, high-quality acceleration of positron beams analogous to the
acceleration of electrons in the blowout regime. However, low energy-transfer
efficiency is currently a limiting factor for future collider applications. We
explore the addition of a secondary electron bunch in the electron filament
plasma wakefield acceleration scheme to recover additional energy from the
wake. Particle-in-cell simulations using HiPACE++ are used to demonstrate
various energy recovery schemes. In addition to confirming the energy
efficiency gains with a recovery electron beam, we also develop energy recovery
schemes in the context of future plasma colliders.
