I think betting on the fights in the Arena would be an interesting way to LSC your luck.
You could set it up so that there is a command that automatically chooses one of the two fighters to be suggested as the winner something like [arena predict] maybe. If the player then bets on that character they predicted would win they get a boost to their LCK LSC depending on how much they bet. Predict would eliminate people trying to break. Another plus of doing this would be it could also help get rid of excess ryo that seems to be floating about at higher levels.