Lindsay Lohan -- Judge Orders More Therapy to Avoid 'Certain Failure'

The rehab facility that Lindsay Lohan has called home for weeks sent a letter to the judge in her probation case ... saying LiLo will lapse back into drug and alcohol abuse if she doesn't get more court-ordered therapy ... and guess what, the judge agreed.

TMZ obtained a copy of the letter from Cliffside Malibu, in which CEO and founder Richard Taite tells the judge, Lindsay needs 3, 50-minute sessions a week for the next 15 months (18 months from last May). Then Taite gives an ominous warning: "If these sessions are not required by the court and attendance verified once a month to ensure accountability, it is a set up for almost certain failure."

The judge agreed in open court this morning, and ordered that Lindsay stay in therapy and prove a year from November that she's complied.

Meanwhile in court, Lindsay's lawyer Shawn Holley showed up with proof Lindsay successfully completed her 90 days of rehab.

Outside court, Shawn talked about "Lindsay 2.0." ... and made a bold prediction about her client's future.