Whats the best lotion for KEEPING a tan?

Im not going tanning, I don't want tanning lotions. Im already tan, I would like to know of a good lotion to help stay tan longer. And please, I don't want any of them sunless tanning lotions that turn your skin orange and make you look like you have a skin disease. I spend alot of time in the sun, Im already plenty tan. Would just like a lotion to help my tan last longer.