Does sitting on your sofa remind you of sitting on the high school's bleachers? Or, on the other hand, do you sink too far into the couch when you sit down? You don't need to spend thousands on new furniture. You just need to give your sofa a "facelift" by restuffing the cushions.
Purchase an inexpensive memory foam mattress pad. The size you need will depend on the size of your furniture. For example, if you're working on a love seat, you'll likely need only a twin size mattress pad.
Measure your sofa's cushions. The measurements don't have to be exact. Let's say your cushions measure approximately 20 by 35 inches. Subtract 2 inches from each number, giving you 18 by 33 inches. Now, create a pattern for yourself. Use a marker to draw a square/rectangle on the foam pad using your calculations, and cut along the lines. Do this for however many cushions you need to make.
When you take the cushion off the sofa, you will most likely find a zipper on the back of it. However, if you're working on a sectional, you may have to feel around the edges to find the hook-and-loop fastener access. Fold a foam square in half and stuff it into the cushion. Position it smooth side up, on top of the existing stuffing. If your current stuffing is completely broken down, replace it entirely with multiple squares of foam stacked on top of each other.