The trial had been scheduled to start with jury selection on Oct. 14. Arapahoe County District Judge Carlos A. Samour Jr. didn't immediately set a new date.
A report on the evaluation had been due Aug. 15, but the state mental hospital said it would need until Oct. 15, one day after jury selection was to begin.
Samour said he had little choice but to grant the extension.
He said he would set a new trial date at hearing on July 22, which will be two years and two days after the shootings.
Holmes pleaded not guilty by reason of insanity to charges of killing 12 people and injuring 70 in the July 20, 2012, attack in the Denver suburb of Aurora. More than 400 people were watching a midnight showing of "The Dark Knight Rises" at the time.
Prosecutors are seeking the death penalty.
It's the third time Holmes' trial has been pushed back. The first date, in August 2013, was canceled after prosecutors said they would seek the death penalty, raising numerous issues that had to be resolved before trial. The second, in February of this year, was scratched after prosecutors asked for the second sanity evaluation.
A sanity evaluation by the Colorado Mental Health Institute at Pueblo is mandatory under state law for anyone who pleads insanity.
The first evaluation was done last year. The key finding — whether Holmes was insane at the time of the shootings — hasn't been made public, but prosecutors objected to the report, saying the doctor who conducted it was biased.
After a hearing that was closed to the public and the news media, Samour ruled the first evaluation was inadequate and ordered the new one.
Under Colorado law, the trial jury will determine whether Holmes was legally insane, defined as unable to tell right from wrong because of a mental disease or defect. The state hospital's sanity evaluation will be a pivotal piece of evidence in that decision, but it isn't clear whether both examinations will be introduced.
Holmes' lawyers have acknowledged he was the shooter but say he was in the grips of a psychotic episode.
Samour's order postponing the trial also disclosed that the person who will re-evaluate Holmes plans to videotape the examination. The examiner said that is his routine practice, and he offered to withhold the videotape from prosecutors and the defense if Samour ordered him to.
Samour didn't issue an order, saying neither side has requested one.
The new examiner was chosen by the state hospital. The examiner's name and credentials haven't been made public, but Samour has said he doesn't live in Colorado.