Press Right, Left, Down, Up, A, B at the title screen. Then, press Start for a one player game or Select, Start for a two player game.
Sound test
Hold A + B and press Start at the title screen.
Replay game with previous score
Complete the game once and return to the title screen. Press A, B, Start at the title screen to start the game again with your score intact and three lives.
Replay game with previous score and lives
Complete the game once and return to the title screen. Press B, A, Start at the title screen to start the game again with your score intact and the lives accumulated in the previous game.