I have done this before, and what I find really strange is1 - How my fingers remember random sections that my brain consciously doesn't. 2 - How some areas I knew so well were completely lost by both my fingers and brain almost like I am learning it new for the first time again. I find running through the piece multiple times and establishing the parts I don't remember, not only sometimes prompt me to remember other bits, but also give me areas to focus on so I'm not really completely learning the whole piece again. Maybe that will help, but I am a memory learner rather than referring from the score much at all, so I don't know if that' makes a difference