Color fade is definitely a problem, especially during summer months when your hair is exposed to sun, chloride, salt water and more. There are some great products available now that will keep your color refreshed. These shampoos and conditioners deposit color each time you use them. Your hair will maintain its vibrancy and color tone.
One of the best out there is Pravana Nevo Color Enhancer. This is an enriching conditioner that comes is Honey Blonde, Brillian Copper, Radiant Red, Deep Burgundy and Cocoa Brunette. Tressa Watercolors shampoos & conditioners also come in multiple shades and really keep color true.
Blonde shades are the hardest to keep pure. Redken's Blonde Idol is a sulfate-free shampoo and custom-tone conditioner...just calibrate to preserve tonality. If you're a platinum blonde, Pureology's Perfect4Platinum Cool Blonde Enhancing Treatment will nix out the brass for up to three shampoos. It's a rinse out violet treatment and perfect for cool blondes that swim!