Once a marinade or sauce has come into contact with raw meat it is no longer safe to consume. But this doesn't mean that you have to throw it out when you are done marinating. Pour any marinade or sauce that you have used on raw meats into a sauce pan and bring it to a boil. This needs to be a complete boil to ensure that all the bacteria is killed off. Remember that food borne bacteria dies at 165 degrees F. Now your marinade or sauce is safe to use as a basting sauce or mop right up to the moment you remove foods from the grill.
One thing to remember, not all marinades tolerate being boiled well, so taste your boiled marinade before you use it again to make sure that the flavor has not been altered by boiling. Most marinades will be unaffected but you never know what might happen.