This isn't your father's Applebee's anymore: CEO

Applebee's is in the process of a major makeover to attract more younger millennial customers while not losing its base of baby boomers, said Julia Stewart, CEO of DineEquity, owner of the casual dining chain.

Stewart told CNBC's "Squawk Box" on Wednesday that renovations at all Applebee's locations will be completed by the end of this year. "You'll see a much more modern and contemporary and much more relevant casual dining restaurant chain."

Trying to appeal to twentysomethings and thirtysomethings, the comfort food chain also plans to step up its bar game.

"Over the next couple of years, you'll see more activity in the bar for the millennial. You'll see more effort focused on the menu at the bar—what we call shareables," Stewart said.

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Source: IHOP

Shares of DineEquity, which also owns IHOP—a.k.a. the International House of Pancakes—are basically flat so far this year. But in the past 12 months, the stock is up about 27 percent. Since Stewart took over as CEO in 2002, DineEquity has risen 130 percent.

While retooling Applebee's, she said she's thankful for IHOP's broad appeal. "If you think about it, you'll find in a parking lot on a Sunday a beat-up Volkswagen and a brand new Mercedes. We appeal to everyone: families, couples, singles."

—By CNBC's Matthew J. Belvedere.