There is no simple, easy yes or no answer to this question because the answer depends on several factors. If you are planning to reupholster an old sofa then you should really consider them before you commit to an expensive undertaking.
It is true that you are saving this furniture from potentially going to a landfill, know that reupholstering an old sofa could end up costing more than you would pay for a new one. Even after you have it reupholstered, it could still be uncomfortable. I am assuming you just mean to have the sofa re-covered, and are not planning to change its insides.
Going to such expense is only be worthwhile under a few conditions, and here they are:
If It's a Family Heirloom
If the sofa has been in your family for a while and has been a prized possession with a history and special sentimental value, you may want to hold on to it. There are certain things which are irreplaceable, and you cannot put a monetary value on them.
If It's a Valuable Antique
When you have a sofa that dates back over a century, and you have invested good money in it, reupholstering it makes sense. This is not something that can be replaced by a brand new sofa. In this case, by reupholstering, you are actually restoring an antique. However, if this is an investment, this should not be attempted on your own. Get a qualified professional to do it, and it is going to be costly.
If It Has Good Bones
It makes sense to reupholster if your sofa is very high quality or has an unusual frame. Quite possibly, the cost of reupholstering it would be less than buying a new sofa of comparable quality. This is not very often the case, but it is possible you may have a perfectly good sofa that can be brought back to life by just re-covering with a new fabric.
Just make sure that it has a sturdy frame and good lines if it is to be considered worth reupholstering.
If It Costs Less
If it is a very good quality sofa, and the cost of reupholstering it comes out less than getting a sofa of comparable value, by all means, go for it. You may want to get quotes from two or three different re-upholsterers for all fabric and parts, and then weigh it against what you would pay for a new sofa of the same quality.
Remember that there is a difference between re-covering and reupholstering. Re-covering involves just replacing the fabric, and it is more of a cosmetic procedure. Reupholstering could involve replacing the padding and springs, mending the frame or re-staining any wood. As you can see a complete re-upholstery job involves a lot of labor and replacement of material, and is more structural in nature.
If you are just tired of the fabric you have right now but don’t want to invest in a new piece of furniture, you may also want to look into slipcovers. I would definitely not recommend reupholstering in that event.
In the end, it is simply a question of finding the best value.