FOund this. Take some drugs and increase your speed.
Acetyl-L-Carnitine supercharges speed and performance
Acetyl-L-Carnitine is an amino acid derivative that occurs naturally in the body. It transports fats to the mitochondria (the energy producing structures inside cells), and is also available as a dietary supplement.
Dozens of studies have been done showing that Acetyl-L-Carnitine (ALC) supercharges cellular energy production in order to maximize memory, health, and longevity. In order to prove that ALC has a positive impact on young people, as well as old, Italian researchers tested 17 healthy young men and women aged 22 to 27. Ten of them were physically active and played competitive sports regularly. Seven of them were pretty much sedentary and rarely exercised. Each one was given either 1500 mg. of ALC or a placebo for 30 days, and tested before and after treatment using a video game-type device designed to evaluate attention span and eye-hand coordination and reflexes.
The group that took ALC had a markedly increased reflex speed. That group also had a reduced number of errors and shorter task completion time by three to four times over the group that took the placebo. No one had any negative side effects.12 What a great way for active, young people to increase their performance speed and reflex time!
site
Other than that, I couldn't really find any definete reflex speed increasers. It looks like it's an innate ability of your body. You can increase your reaction time by practicing situations that you want to be faster at resulting in a faster "reflex" but you can't actually increase the speed of the reflex itself.