MICHAEL DAYS had vowed the last time he ran the Daily News that he wouldn't be the final editor of Philadelphia's scrappy tabloid, and so at Wednesday's announcement that he's coming back, the Pulitzer Prize-winning cartoonist Signe Wilkinson reminded him of that promise.

"And I'm not going to be," Days responded. "I'm not going to let that happen."

Moments earlier, staffers at the People's Paper burst into applause when publisher Bob Hall announced that the 58-year-old Philadelphia native will replace Larry Platt, who's been the Daily News editor for 16 months. Days, who guided the Daily News from 2005 until the start of 2011, had been serving as managing editor of the Inquirer.

Days promised the hastily assembled journalists that he'll keep what's great about the Daily News, which won the 2010 Pulitzer Prize for investigative reporting near the end of his previous tenure, while pushing that staff to flourish in a fast-changing era of mobile devices and Twitter.

"We all need to be advocating our cause over social media," said Days, who told the staff that to remain popular and relevant in the Internet age "we've got to figure out how to ratchet it up quickly."

But he and Hall were short on any specific changes, and the new publisher said that a controversial system of sharing content between the Daily News and the Inquirer — newsrooms that have long had a fierce rivalry despite common ownership — is still under review since new local owners bought the papers earlier this year.

"We'll be getting it done in a very loud and very irreverent way, and when we need to be very obnoxious, in a very obnoxious way," Days promised.

Platt, who came from Philadelphia magazine and whose tenure coincided with the short reign of unpopular hedge-fund owners, told reporters in an email that he'll be focusing on a book he's writing with former Phillies pitcher Jamie Moyer and that he'll write a column for the Inquirer.

"I have long loved the Daily News, and I was jazzed by the challenge of being a change-agent, of remaking the publication that I grew up poring over," Platt wrote. "And, boy, did we embark on some change: a redesign, a new focus for both news and features, an entirely new product, SportsWeek, a new content-management system. It often feels like the last year and a half has been nothing but change, some of them wrenching."

With Days' return, everything old is new again at the Philadelphia newspapers and at Philly.com since they were purchased for $55 million by the local group topped by parking-lot mogul Lewis Katz and Camden County politico George Norcross. The new owners restored Hall as publisher and brought back Bill Marimow as editor of the Inquirer, and the new management has even brought back former columnists such as the Inquirer's Clark DeLeon and the Daily News' Harry Gross.

That was the easy part. Now comes the hard part: keeping readers and bringing in new revenue in the age of the iPad.