To edit your civilization's level, go toMy Documents\My Games\Age of Empires III\Savegame. There, look for the ".xml" file you want (it should have your HC's name... like sp_Berlin_homecity.xml, sp_London_homecity.xml). Open it with a text editing program (like Notepad) and edit the<*level> and<*skillpoints> tags. The first will change your XP/Level, and in the second you should put the number of available cards you want. Example: If you put 42, you'll have 42 points to spare in cards.