Here's the deal... I've passed multiple drug tests with only have stopped smoking four days before them.
Drink, drink, drink. I was going through two gallons of liquid if not more a day. Not just water, ANYTHING, water, juice, beer, hard liquor, just always have a bottle of something next to you.
With two weeks, simply drinking a lot you might be able to clear out (if you have a relatively high metabolism).
I would suggest going to a head shop and buying something similar to
Detoxify. Follow the directions directly. They usually involve drinking the full bottle (2-4 hours before your drug test), and then filling that bottle with water, and finishing it within 15 minutes, and then simply drinking a certain amount of water or more between then and the test. Both times I have had to use such drinks they have worked.