When you get to Chapter 11 which is almost at the end, there will be a room where you have to open by using a power node, so be sure to save some for later use in the game.

Open the room and take the power node and ruby chip then continue on to the next few rooms and there will be a room with a save point, store, and bench.

For the cheat to work all you have to do is save and then restart from the checkpoint.

When you restart, everything in the power node room will re-spawn.

Go get the items and just keep redoing the process. If all the items don't re-spawn then just restart until it does.