To achieve a proper cure, exact mix ratios are critical when working with epoxy resin and hardener.
Adding more hardener does not make mixed epoxy cure faster—it alters the mix ratio and results in an improper cure.
To make the epoxy cure faster, you can raise the ambient temperature using a space heater or a heat lamp—colder temperatures slow curing; warmer temperatures speed up the curing process.
It's actually the hardener, not the resin, that determines the cure speed. If you need a faster cure, you can use a fast speed hardener. Traditional epoxy resin systems such as West System 105 and TotalBoat 5:1 Epoxy Resin have a fast cure speed hardener: West System 205 Fast Hardener and TotalBoat 5:1 Fast Epoxy Hardener.
2:1 epoxy resin systems (MAS 2:1 Epoxy and TotalBoat High Performance Epoxy system) have three available hardener speeds: fast, medium, and slow. The different hardener speeds can be combined to get the desired cure time and pot life for your project. Keep in mind that the exact ratio is always required in order to achieve a proper cure.