His coaching career has spanned four decades and will now likely come to an end in the summer of 2015, since his latest contract was back-dated to September.
The former Berwick Rangers, Hearts, Bradford City and Kilmarnock manager had intended to retire at age 62 but has been rejuvenated by the challenge of rebuilding a team at East End Park.
"Before I came to this club, I never envisioned myself coaching until 2015," said Jefferies, who has retained Neil McCann as his assistant. "I certainly don't see myself as a Sir Alex Ferguson or a Craig Brown . . . our training ground doesn't have facilities for a 70-year-old manager."