Since it sounds like you've already basically learned it before, I find it helpful to play it through very slowly with a metronome, not trying to do anything expressive. This will re-connect the notes in your brain. Do this at least once a day. VERY slowly.
After that, break it up into small chunks and work on fingering and phrasing. If it's easier to do hands separate that's fine, although I don't know whether that would work with this piece. Again, don't try to bring it up to tempo, but now you can play it as fast as you can without making mistakes. Don't worry if you're doing different parts of the piece at different tempos, you can fix that later.
And then finally, at least once a day, try to play it all the way through, incorporating everything you've already achieved. Here it doesn't matter if you make mistakes, you're just trying to have the experience of playing the whole thing without stopping.