The troubled starlet joined friends -- including actor Emile Hirsch -- at Lexington Social House by 11:00pm local time Wednesday.
The former child star even stumbled as she headed for her car -- but this time, blinding camera flashes rather than alcohol were to blame. Lohan, 24, appeared to be drinking non-alcoholic sodas throughout the night before leaving around 2:00am local time Thursday.
But "her focus right now is resuming her community service obligation," her spokesman Steve Honig told NewsCore. "She is really eager to fulfill that obligation. She takes it very seriously."
Lohan is now set to begin community service at a homeless shelter and a morgue.
She was placed under home confinement at her Los Angeles condominium, in lieu of 120 days in jail, after pleading no contest to misdemeanor theft in May -- a violation of her probation for a 2007 DUI charge. She was deemed eligible to serve her sentence at home due to jail overcrowding.
But Lohan is not yet in the clear. She now needs to dedicate 360 hours to helping at a homeless shelter for women and doing 120 hours of janitorial work at the Los Angeles County morgue as part of her plea deal.
Despite the work still ahead, Lohan will travel to New York to celebrate her 25th birthday with her family Saturday, E! News reported. She is also rumored to be among the guests invited to the "L.A. Takes Over the Hamptons" party that day.
"I want to be in nyc," she tweeted earlier this week, alluding to her longing to be back in the Big Apple.