Back in the day, Coca-Cola gave us an object lesson in how NOT to change your product. We all remember it. They wanted to reinvigorate their brand by refining the formula for Coke. After extensive research, including focus groups which universally lauded the new product, they released New Coke to massive fanfare.
After a few months on the market, it was pulled and Classic Coke went back to being just plain Coke, the kind we still drink today.
This time around, a company finally gets it right when it comes to redoing their product. Of course it helps that their product was pretty terrible to begin with. Domino's Pizza overhauled their pizza formula after 18 months of growing criticism. Rather than close their ears and hide from the poor reviews, they embraced it. After a guerilla ad campaign that showed diners criticizing the pizza, comparing it to cardboard with sauce, Domino's is back with a new pizza and revived sales to show for it. The company profit has more than doubled in the wake of the new recipe and campaign.
I can't vouch for the quality of the pizza, not having sampled it. But from a marketing and crisis communication standpoint, the company did everything right. They admitted there was a problem, they addressed publicly in a memorable and humorous way, owning the story at every step.
The commercials got people talking, the new product got people buying.