Note: This procedure requires editing a game file; creating a backup copy of the file before proceeding is recommended. With a text editor, edit the .xml file in the "save" folder in the game directory. Locate the "Resdepot" entry. It will appear similar to:
ResDepot type="1" amount="94472"
Type 1 is gold. Type 2 is supplies. Type 3 is food.
Change the amounts to "100000". When you play the next level you should have 100,000 in all three categories. When the level is completed you can use your resources. Repeat as desired.