Successfully complete the game then after watching the credits, save your game. Load this end-game save to start the game over with the money and the characters' EPs from your end-game save.
Bonus Demo Level
Successfully complete all demo levels and save the game. Load the cleared game, then highlight the first level on the selection screen. Press Up + X to enter the Wanzer Shop. This will start the secret bonus demo level.
New Game Bonus
Clear the game once and save your "Game Clear" data. Loading that same file will start you on a new game with a 700-900 EP bonus for all your pilots (which makes customising them a hell of a lot easier). You also carry over all the money from
your previous game, but not any purchased or unlocked weapons or parts.