LOS ANGELES &#8212 Lindsay Lohan’s best bet for avoiding jail time is to go back into rehab yet again and remove herself from a high-flying party lifestyle – if not, she could be facing up to six months behind bars, legal observers said Wednesday.

Lohan, 21, was less than two weeks out of a recovery program and was voluntarily wearing an alcohol-monitoring device when she was arrested Tuesday in Santa Monica for investigation of misdemeanor driving both under the influence and with a suspended license, and felony cocaine possession.

Her lawyer said she had a “relapse” and was receiving medical care at an undisclosed location.

The actress completed more than six weeks in rehab less than two weeks ago, and had checked into another recovery clinic in January.

Over the weekend, she was photographed at a party in a pink bikini, with the monitoring device on her ankle.

That behavior won’t cut it anymore and neither will spa-style clinics, said Barry Gerald Sands, a Century City defense attorney who’s also a certified drug and alcohol counselor.

“Whatever you have done in the past, do a 360-degree turn and go the other way,” Sands said Wednesday. “She has to change her alleged friends, people sharing or selling her drugs. She has to lead a clean and sober life.

If Lohan is charged, she could ask a judge to order her to remain in rehabilitation while she awaits trial, Sands said.

A “recovery team” should be in place that includes doctors and addiction specialists who can give the judge alternatives to jail. If she is convicted, the rehab time would count against the issued jail sentence, Sands said.