Greg Cunningham is set to be sidelined for a spell after being injured in the midweek draw with Huddersfield.
Earl came off the bench to replace him and is a likely starter against Peterborough at London Road tomorrow.
Lowe thinks Earl is lacking a bit of confidence with the attacking side of the wing-back role and has urged him to believe in his ability.
“Josh needs to do a little bit better for us, he’s 6ft 3ins, he is a powerhouse,” said Lowe.
“He should be taking the ball on and not having it taken off him.
“I want him driving into the final third, I don’t want him to be safe and coming back.
“It’s an opportunity for him to showcase. When I first came in, Josh was fantastic.
“Now I want to see a little bit more, especially in that final third – more threat and more quality.
“If Josh brings that to the party he can be an unbelievable player.
“What I’m saying to Josh is that if he sees grass, run into it, don’t come inside where there are bodies and the chance of giving the ball away.
“When you give the ball away there is the potential of having to run 40 yards back the other way.
“Brad Potts on the other side was fantastic in midweek, he pegged Huddersfield back.
“If Josh can do that on his side of the pitch, he has so much to offer.
“Sometimes we can be a bit safe. Anything in the final third I will take responsibility for, so go and risk it.”
Cunningham went for a scan yesterday having pulled up in the first half on Wednesday night.
An injury in the calf area is the issue, with the initial concern being it might have been his Achilles.
The scan results have to be looked at by a specialist for a diagnosis.
North End hit the road for a third time in the last four games when they travel to take on the Posh.
Darren Ferguson’s side were beaten 4-0 at Cardiff on Wednesday night,
Lowe said: “I look forward to any game of football. We are in good form, keeping clean sheets, creating chances.
“We won’t underestimate Peterborough, just because they lost 4-0 at Cardiff doesn’t mean we will automatically go there and win.
“We have to get it right , our attitude and application has to be spot on.
“I have come up against Darren Ferguson teams many times, they will want to put it right sooner rather than later.
“I know how hard Darren works, that they are well coached and well drilled, they have some good players.”