Jessica Manzanero, 29, was found dead in her apartment on the 500 block of East Moore Street in Norristown on May 4, 2011.
An autopsy found the mother of two had been stabbed multiple times.
Investigators believe she was killed about two days earlier.
District Attorney Kevin Steele said Monday that detectives have uncovered new details in the case.
A $2,500 reward is now being offered for any information that leads to the arrest and conviction of the person responsible for Manzanero's murder.
Anyone with information is asked to contact Montgomery County Homicide Detectives at 610-278-3386.