Leather conditioners work by reintroducing natural oils to the surface of leather goods, thereby increasing their suppleness. These conditioners are formulated to work with leather and prevent future drying and cracking of the material. After wiping down the surface of the couch with leather cleaner, work a small amount of leather conditioner into the surface of the couch using a soft cloth. Repeat as needed.
These multi-step kits can be found online or ordered from furniture stores. The kits come with leather cleaner, dye/colorant available in an array of colors to match your couch, applicator sponges, and leather conditioning cream. The kits are used to change the color of the couch or recolor parts of the couch that are worn and faded. After cleaning the couch, you apply several layers of the colorant, allow it to dry overnight, and then treat the couch with the leather conditioner to prevent future wear and fading.
This balm differs from the aforementioned kit in that it is a single-step process that involves swiping a small amount of product on the surface of the couch to fill and recolor worn areas. After drying, this color-matched balm blends in with the rest of your couch.
If you have small children or pets, or are just trying to take small steps to live a "greener" lifestyle, there are some all-natural products you can use on your leather to repair signs of wear or mild scratches. Orange tree oil, olive oil, or neatsfoot oil can be sprayed in a thin layer on the couch and the excess wiped away with a dry cloth. This can cause temporary darkening of the leather, but if you spray the oil all over the couch, the color will be even.