"Bring it in" is like this: So before the game the whole team comes together for a "huddle". Every one is in a circle and then you put your hands in the middle and say, "One two three... (team name)!" Sometimes a coach says, "bring it in" which means, "Okay, come together. Let's talk".
"Bring it on" means, "Give me the challenge. Bring the challenge. I am ready."