After dying the 3rd time (when you're about to get a game over) and right after your ship blows up, press Start on another controller and join in with a new character. Your first character will come back to life. Then just quit with the second character, and keep playing until you die again.
Press Start on controller two immediately after your last ship explodes to continue game play. Then, have player two quit the game and player one will be able to continue.
Extra credits
When you finish escorting a ship to its destination, stay with it after you are paid. The ship and the others will destroy enemies for you, leaving credits behind. At times, you can receive 200 to 300 credits before returning home.
