The three judges said the man’s early guilty plea, genuine remorse and chances of rehabilitation warranted the change.
The man will now be eligible for release after serving a minimum of eight years and five months of his sentence, a cut of 17 months.
The attack in the suburb of North Lakes, about 45km (30 miles) north of Brisbane, sparked community outrage and was among several cases which prompted the state of Queensland to controversially introduce stricter youth crime laws.
During the trial, the court heard that Lovell and her husband had confronted the two intruders, both teens at the time, in their home before forcing them out onto the front garden where a struggle broke out.
Lovell was stabbed in the heart with a knife, with ambulance officers performing open heart surgery on her while her two teenage daughters watched on. She died shortly after arriving at hospital.
The court of appeal judges found that her murderer’s 14-year sentence was not “manifestly excessive”, agreeing with the sentencing judge that the murder had been a “particularly heinous offence” which had provoked “a sense of outrage”.
However, the requirement that the man serve 70% of that sentence was excessive in light of an early guilty plea which had saved the victim’s family from the trauma of a trial.
The judges also found the man’s troubled upbringing – exposure to violence, parental neglect and excessive alcohol and drug use – should also have been given more weight when considering the timeline for his release.
The second teenager involved in the attack was cleared of murder but last December sentenced to 18 months detention for burglary and assault.