Inspect the old sofa in bright light to find rips, holes and worn areas as well as spots and stains. If the upholstery is torn or worn through, cleaning probably will not be enough to save the sofa. Consider covering it after the cleaning is complete.
Vacuum the old sofa's front, back, sides and bottom surface. Much of the soil may actually be removed with a thorough vacuuming.
Clean the sofa, giving the spots and stains special attention. Soil may be removed with a sponge or rag and a mixture of warm water and laundry detergent. Change the cleaning solution frequently as it becomes dirty. Add white vinegar to the mix for stubborn stains, and select a commercial upholstery cleaner if necessary.
Inspect the appearance of the sofa when it's clean and dry to determine if further steps must be taken to restore the piece's beauty and function. Nothing more is necessary if the sofa looks satisfactory. If not, consider covering it.
Purchase or make a throw to give the sofa a new appearance. These loose covers are not fitted to the furniture and may require being tucked into spaces between the cushions, back and sides of the sofa. New pillows or pillow covers will add to the fresh look. This is probably the least expensive way to recover the sofa. Choose washable fabrics.
Acquire a slipcover for the sofa, being sure to buy a cover intended for a sofa with attached cushions. Slipcovers are available at many retail outlets, both online and in stores, at many price levels. The slipcover is fitted to the furniture, may be equipped with zippers, and generally remains in place. A slipcover should be washable.
Choose the most expensive option: reupholstery. Hire a professional upholsterer, or secure the services of a vocational school or a student upholsterer at a reduced cost. You might choose to reupholster the sofa yourself, purchasing the fabric and consulting online instructions or instruction books.