how to keep fair dye to last longer ?

Joseline
I recently dyed my hair with Temportary hair dye. I dyed it about almost 2 weeks ago. The color is like a red,  hint of purple , and pink ...I guess more so like a magenta . 
I really like the color and I really want to see how long it lasts. What are good products to maintain the dye in a little bit longer (if it's possible) I already bought shampoo and conditioner for color treated hair but today when I washed my hair, a lot of the dye "faded" out.. Good thing only on the bottom part of my hair. 😕