In-between Salon Care

HI LADIES!!!

I am a natural blonde who went through some damaging dye periods about a year ago. I go to the salon about once every three months to get my hair highlighted so I can return to my natural color. I don't want to go more often, because I am afraid my hair will get damaged.

Now, my question: is there anything I can do inbetween my salon visits that will make my hair lighter shades of blonde? I read about lemon juice, but I am afraid it will damage my hair. I was thinking along the lines of a lightening shampoo - subtle and not dramatic. Can you reccomend a good product?

Thanks in advance for all your tips.