Make sure you are using the correct fingering and the SAME FINGERING each time - this is crucial if you want to get faster!
Make sure you can play the piece the whole way through in each hand (separately) at each speed before moving on the next speed.
You may need to practise with a metronome to help bridge between the different speeds.
Once you can play each hand all the way through at 160, then go back to 75 with hands together and repeat the process.