Stalled plans for a 569-foot residential and retail tower that would rise above Copley Place are back in play with a proposed additional 224 residential units.

Simon Property Group yesterday revealed revisions to the $500 million project that call for a 52-story tower with 109 condos and 433 apartments while keeping the building’s height at a previously approved 569 feet.

The changes come a year and a half after the Indianapolis-based mall owner won Boston Redevelopment Authority approval for a 47-story tower with 318 condos, a 54,000-square-foot addition to the Neiman Marcus store and 60,000 square feet of retail and restaurant space.

“Once we got approval … we further looked at the market, and we weren’t comfortable with (it) at that time and its evolution,” said Patrick Peterman, Simon’s vice president of development. “We felt like adding apartments was the prudent thing to do. We feel we’ve really got the right program now.”

With a four-year construction timeline — the tower will be built on state-owned air rights over the Massachusetts Turnpike — the company had to “look out to the future,” he added.

The tower would be among the city’s tallest residential properties. Simon also redesigned both its street-level base and a publicly accessible atrium.

“It should be almost a requirement that projects take a two-year hiatus, because this is much-improved from when the project went on hold,” said David Berarducci, a South End resident who is on the project’s citizens advisory committee.

Simon’s proposed changes require city and state approvals. The company said it would file necessary paperwork with the BRA in the coming weeks with the hope of starting construction in spring 2015.

“We’re pleased that Simon Property Group is re-engaging in their Copley Place project, and we’re looking forward to working with the community and the development team on next steps,” BRA spokeswoman Melina Schuler said.