Ways to practice shooting hockey pucks in garage?? and harder wrist shots?

i am trying out for jv team this year and i have a great chance but i dont wanna sit back on it. i wanna give it the extra effort i have been shooting 300 400 pucks a day out in my garage. i have a board of synthetic ice to shoot off of but i feel like im standing still to much and it wont help me in a game situation? any ideas so practice otherways? and how to improve shot power? i do writst rolls and stuff