You may think I'm reaching with the medical term "ischemia," but follow my train of thought for a moment, if you will. Ischemia in terms of health refers to an area of the body receiving too little blood--the area becomes pale and can die.
The same thing can happen with your writing. If you run out of writing mojo, your writing projects may become pale and lifeless. It's tough because the bills and expenses keep piling up, but taking a day for yourself now and then may be just the thing you need to pump blood and life back into your writing.
You say there's no way you can take a day? Then take an hour or two and do something that re-energizes your batteries. For a whole lot of us, the best thing we can do is get some physical activity. Freelance writing is such a sedentary profession; physical activity is just what the doctor ordered--and maybe your writing muse, too.
At the first signs of writing ischemia, take a time-out.