There are currently no ways to earn lives, coins or boosters for Juice Jam. Creating rewards for players is something we're looking in to, as we're aware it can be frustrating when completing a level or being a regular Juice Jam player doesn't reward you with any coins or boosters.
All our levels can be completed without the use of any boosters or additional lives, they're simply there for people who want the additional help. Each level is designed to be beatable without the use of boosters (our level designers have never used a booster in their life!).