Completion bonus:
Successfully complete the game, then save when prompted after the credits. 
Select that saved game from the main menu to play again with all the EPs and 
money from the previous game. 

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. 

New Game with Completed Game Save:
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.