Start learning your pieces from the back.Let's say, your piece has 32 measures. Start with measure 32 (or 31-32, or 30-32). Then add the next (few) last measure(s) and play to the end. Continue until you added measure 1. The result is amazing!
Question:how do i complement that HAND memory (that i know is necessary, after all), that betrays me so often, with a much more reliable one?
If you wanna complement hand memory, practice your pieces slowly very often. Very Slower tempo = forces you to not use hand memory.