Alot of it depends on how much you smoke and how often. Also your metabolism and body type...
I know some things not to do: Dont work out or go running 24-48 hours before you test.. Dont get any message treatments.. These types of things release toxins stored in your body.. Stay away from other smokers,, my room mate just lost her job cause me and her husband smoke all the time and shes around it thus she popped positive for weed..
Sauna is also a bad idea before your test..
Since you got 2 weeks,, get some hydroxycut or ripped fuel something of the sort, and go running and work out.. Increase your water intake of course.. Try drinking 2 full glasses of water with 10 min of waking up.. That will kick start your metabolism into high gear aswell as help flush your system...
Worst comes to worst get a whizzanator,, i have had good luck with that camping kit for making potable water..