The court and prosecutors "had a problem with some of the work shadowing," said Lohan's attorney, Shawn Holley. "They didn't want to hear more about how that played out."
Judge Mark Young's decision Wednesday means the actress will not be able to put a period to her probation in March but will have it extended for another three months so she has time to complete the extra 125 hours.
Lohan was ordered to perform 240 hours of community service as part of a plea deal she made after she was convicted in 2012 of reckless driving. Her Porsche rear-ended a truck on Pacific Coast Highway, and Lohan denied after the accident that she was behind the wheel.
The decision was made behind closed doors, and the judge made a brief announcement in court following his decision. A proceeding will be held March 12 to decide how Lohan can complete the community service in an acceptable way.
Holley said Wednesday her client "doesn't have a problem" with the added community service hours.
"She's enjoying doing community service," Holley said. "Her passion is really working with kids ... and kids really respond to her."