They had something called Diet Pepsi greatest hits where Lemon Pepsi came back in diet form

Diet Pepsi Greatest Hits

Maybe they should do Pepsi's Greatest Hits or something similar where they bring back several non diet flavors for a limited time only with *real* sugar

Pepsi Lemon
Pepsi Lime
Pepsi Vanilla

Create another Cherry Pepsi, or change the current one....

Pepsi Wild Cherry / Pepsi Cherry (could either go all cane/beet sugar for 8 weeks, or another name could be given to an all sugar version like 'Pepsi Cherry' in order to keep the regular HFCS/sugar Wild Cherry formula while testing the real sugar version)

These should be available in 20 oz, 2 liter, and 12 pack cans. These flavors can do better with real sugar and Pepsi should try these flavors again for 8 weeks.