Most of your fails will come through being caught via police or the bouncers, you rarely die really which makes 100 deaths an annoying number.
In my opinion the fastest way to get your remaining deaths (I had only died 21 times once id completed the story) is to load up the 'Glow Neon Party' and immediately start slowly pressing
over and over (Credit to WhyattThrash
). This will trigger the speaker trap that you always spawn next to and once dead will also restart the level for you. If you keep pressing whilst the level is loading the trap actually triggers before the level is fully loaded and you will find that the level starts with the speaker on fire and the countdown for it at 50-60%.
I found it a good idea to snap the achievement app whilst I was grinding this out to see how far off I was. I went from my 21 deaths to 100 in around 20mins.
Here's a video