The bench of Justice R R Prasad allowed the extension plea petitioned by Mishra on medical ground.
Mishra, who was granted provisional bail on October 25 last year till January 8 on medical ground, is now under treatment at a hospital in Delhi.
Along with another ex-Bihar chief minister Lalu Prasad Yadav and 43 others, Mishra was convicted in the RC20 A/96 case on September 30.
He was sentenced to four years in prison by a special CBI court on October 3.