I wouldn't strip your hair, you don't really need to remove color anyway, you just need to add it. Stripping does damage hair, whether you can notice it or not, especially for what you say the condition of your hair is in. I had bleached blonde hair and didn't like it so got a darker red semi-permanent color added. I did it all at a salon. It faded a lot, but the main color of the semi has never gone away. This might have been because my hair was very bleached so it was open enough to hold all that color in there permanently, so I don't know if yours is bleached enough to take and hold onto a semi, but I would do that anyway. I am going to do another semi color myself this time, due to the color actually being lighter than my roots, but I think I won't have to do it again after this time, and if I do then I'm sure it won't be often. Of course, even if the semi sticks to the part of your hair that's been bleached, it will still fade off the roots, so you should try to get a shade that matches your natural color or close to it, whatever you think is best. It might fade a bit, so you might have to keep doing it every so often. So that's my advice, I think that's what you should try. Oh, and I've heard that you should be careful not to choose an ash color. And if you're doing it at home, I think I've heard that L'Oreal is one of the best brands, but also I've heard that Sally's Beauty Supply has some good brands and I think they are supposed to be able to help out. Otherwise, a salon would be the best bet. And be sure to buy yourself shampoos and conditioners for color treated hair, and use a good deep conditioner weekly! Good luck!