Does the baking soda have to be new in order to clean an urine analysis for meth?

Whether the baking soda is new or not has no influence whatsoever on whether you will pass a drug test. The thing to remember is that if you want to stand any chance of passing a drug test, you want to give yourself as long as possible. This is really what it will come down to, as there is no better way of flushing your system from the metabolites that drugs leave behind than the body's own organic method of disposing of them.

I know that staying off meth is easier than it sounds, but really there is very little else you can really do.

Drinking water and exercising are two things that might help speed up the process, but if you don't give your body time, then it's game over when you face the test.