Hair therapy, Help!?

I used to have extentions for a long time, and then almost 3 years ago I took them out and cut my hair up to my shoulders to a) even it out, as the extensions took a lot of my hair upon removal. And b) to begin getting it healthy again. I have spent 3 years growing out my naturally dark brown/black hair to get it long and healthy. Well, I've become bored with it so I went to a medium brown with blonde streaks. My hair now feels like hay and the ends are brittle. I'm worried that I will never be able to grow it to my old length with the coloring I have recently done. What can I do to protect the ends and keep them from further breakage, and what can I do about a really GREAT and weather proof conditioner throughout the summer?