I've been there done that a bunch of times. I've given up on the notion of quitting fully. At this point I average about a can a day, which is down from the all time high of a 12 pack a day.
And I make that can with my soda stream so it's only half strength diet cola most days. It helps that I'm a coffee drinker, so an extra cup in the morning eliminates withdrawl headaches.
And when I want the taste, I make a 20 oz bottle of crystal light every few days. Then I add about 2 ounces of that to my 32 oz bottle of ice water that comes to work with me every day. I don't need the full flavor crystal light, just a splash in a bottle of water does the trick.