First change background: Dojo -->Sensei Swag --> 1 down: Storm Castle.
Now start Zen mode. When you see under 1 minute on the clock and don't have achievement or not near 75 points, restart the game by holding your hand out and slice retry. This took me a few attempt because I had to get pretty good combo's going to get to 75 points quick. so just keep at it and hope for some easy combo's. Some are easier like when they all line up from when they appear = x5 or x6 combo. For the other combo's just wait for maximum fruit to line up and slice away.
Edit: Must be done in 29 seconds or less.