If you do have a nerve deafness, there is no real treatment. If it has been improving over the years, it is a good sign. However, in case you are being handicapped in your day to day or professional life, I would recommend that you go for a hearing aid. There are small ones (in the ear) which are barely visible but are expensive. Use of a hearing aid will in no way
affect your normal hearing level. If it has to improve or deteriorate, it will do so irrespective. It is just like using spectacles to make you see better.