Publix Curbside, the Lakeland supermarket chain's latest experiment in online grocery shopping, is exceeding company expectations. So far, 80 percent of shoppers who tried it became repeat customers, and a majority of shoppers willing to pay $7.99 to order online drove five to 10 miles to pick up their orders at test stores in Atlanta and Citrus Park near Tampa. Seven months into the one-year test, the chain has decided to broaden the test to a third store that opens as a combination Publix/Greenwise in a few months in Atlanta. There are no plans yet to take Curbside beyond that, said Shannon Patten, Publix spokeswoman. The first two stores test customer pickup from the parking lot or a covered drive-through. The third will use a storefront separate from the Publix store. Publix lost $50 million on its first online shopping experiment in South Florida, which featured home delivery until it was abandoned several years ago.