The flavor, Retro Diet Coke Lime, was first launched in 2004 but was discontinued in 2018, according to TODAY. Here’s what you need to know about Retro Diet Coke Lime’s return to stores. When will Retro Diet Coke Lime return to stores? Retro Diet Coke Lime will return to stores in bottle and cans starting Oct. 6, according to Coca-Cola’s website. Where can you buy Retro Diet Coke with Lime?