Here are two situations in which you should reupholster your sofa.
The upholstery fabric is wearing thin in certain areas
The upholstery fabric on a sofa can begin to wear thin in the areas where it is subjected to regular friction (such as the sections of its arms where you rest your hands whilst sitting on it or the parts of the seat cushions onto which your lower body presses). Thinning upholstery fabric can cause many issues.
Firstly, resting your arms or legs on these frayed areas whilst you're wearing t-shirts or shorts and your skin is exposed could make your skin sore and red. Secondly, the exposure of the sofa's foam internal cushions could damage this material over time, as there may not be enough fabric to protect it from friction or spills. Thirdly, a sofa whose upholstery is thinning in multiple areas is very unsightly and will make the furniture look tattered, no matter how well designed it is.
As such, if you want to protect (and thus avoid having to replace) the sofa's internal cushions, want the furniture to look good and would like it to be comfortable to sit on, you should get it reupholstered.
You've got a new puppy or kitten and a plain, pale sofa
If you've got a new puppy or kitten, it might be necessary to reupholster your sofa. You may need to do this if the current upholstery is a plain, light colour. The reason for this is that whilst you might intend to train your pet to stay off the furniture, it is unrealistic to assume that they will always obey you, and if left in your home on their own even for a short period, there is a good chance they will decide to climb around on or take a nap on your sofa. This could result not only in the sofa getting stained by their dirty paws but might also result in them having accidents on the upholstery (as it can take months to toilet-train a puppy or kitten).
However, if you get your sofa reupholstered with a dark-coloured fabric that has a complicated pattern on it, the stains that your pet leaves on it (as well as the fur they shed) will be difficult to see on this busy-looking, dark fabric. Because of this, as long as you sanitise the upholstery, you should be able to continue using it, as it will still look reasonably good. It should be noted that if you're reupholstering your sofa for this reason, it's best to opt for some fairly inexpensive upholstery fabric, as in a few years' time when your pet is trained and well-behaved, you might decide to switch back to a lighter, plainer fabric.
Talk to a professional to learn more about reupholstering.
