Goals from Kenny Miller and Steven Naismith put Rangers in the driving seat in Saturday's friendly before Lovenkrands netted with his first touch after coming off the bench.
Rangers survived some late pressure against the Championship title-holders to give them a lift before they begin the defence of their Scottish Premier League crown against Kilmarnock next Saturday.
Both sides named their strongest available line-ups with Rangers missing Andy Webster and John Fleck through injury. Newcastle started with Mike Williamson and Fabricio Coloccini, with recent signing Sol Campbell left behind in the north east to work on his fitness.
Joey Barton and Lee McCulloch headed over at either end in an even start before Steven Whittaker put Newcastle under pressure with a positive run and low cross that deserved a better response from his team-mates.
Whittaker started brightly in a wide left position and the opening goal came from his delivery in the 24th minute.
The Scotland international cut back on to his right foot and crossed for Miller to head home at the near post after the striker showed impressive sharpness to find space in the box.
Newcastle pressed for much of the remainder of the half without carving out a clear chance. Striker Andy Carroll was replaced at the break by Shola Ameobi, who did not take kindly to being shoulder-charged on to the track by Madjid Bougherra.
Rangers enjoyed the better of the early second-half exchanges and Steve Harper pushed over Kirk Broadfoot's strike before Miller headed over from a difficult chance after Bougherra had lobbed the ball back in the box.
Rangers moved further ahead in the 66th minute after Newcastle were cut open at the back. Steven Davis ran at the visitors and held the ball well as substitute Kyle Lafferty ran offside before releasing the ball into the path of Naismith, who ran from deep before slotting the ball past Harper and into the corner of the net.
Lovenkrands came on to a huge ovation from both sets of fans in the 30,220 crowd and immediately pulled one back from close range in the 70th minute after Allan McGregor had parried Kevin Nolan's effort following good persistence from Ameobi.
Newcastle pressed but McGregor threw himself to his left to push away Nolan's powerful long-range effort and McGregor denied Lovenkrands an equaliser from close range in the 89th minute.