Change of Venue
No joke, I have moved from the couch and am now writing from a folding chair in the garage while my toddler peddles his plastic car around the driveway. While this particular change of venue was imposed rather than chosen freely, you'll find that moving your work space is an effective way to kick-start creativity and refresh your energy levels when working from home.
Even if you have a dedicated home office, you might try working from the kitchen table or outside on the back porch to restart the workday. Some people find it helpful to leave the house entirely for part of the day and set up "office" in a coffee shop, library or other venue with reliable WiFi access. If you crave the productivity-lifting background noise of a buzzing cafe, but don't want to spend $5 on a cup of tea, try the free audio stream from cofficity.com.