Sounds like normal wear and tear, a simple solution would be to just replace the soles, as the rest of the shoe is fine.
As for repair- there are kits to repair soles, however usually they're meant for quick fixes and not to be lasting repair, some searches can show you a few:
http://www.google.com/products?hl=en&source=hp&q=shoe+sole+repair+kit&um=1&ie=UTF-8&ei=VDwXS5CWKdDdlAeKjN3qAg&sa=X&oi=product_result_group&ct=title&resnum=1&ved=0CB8QrQQwAA
however as stated before, these are usually just for quick crude fixes.