Mr Shaw said it was the same slogan used by the Greens in 2014.
"We believe in recycling," he said.
Sunday's launch was Mr Shaw's first major party appearance since becoming the sole leader.
Former co-leader Metiria Turei resigned on Wednesday, saying scrutiny of her family over her past welfare history had become unbearable.
The Greens had plummeted in a poll due to be unveiled that night, but she denied that was a reason in her resignation.
Ms Turei had been under growing pressure after she admitted to historical offending while on the benefit 20 years ago.
Mr Shaw said it had been a long week for the Greens.
"We started out talking about the problem of poverty in New Zealand. We ended up talking about our problems.
"I want to apologise for that. I want to thank those who have supported us during this time and apologise to those who feel like we've let them down."
Mr Shaw announced a number of changes for the Greens, including running a positive campaign and the reused slogan.
Love New Zealand, he said, goes to the heart of what the Greens stand for.
"Last election over a quarter of a million people voted Green because you love New Zealand. I want you to know we're still the same party with the same values," he said.
Mr Shaw set out three policies the Greens will focus on: poverty, climate change and clean water.
He announced a new caucus leadership team to take on each of these areas - Marama Davidson (poverty), Julie-Anne Genter (climate change) and Eugenie Sage (clean water).
The reorganisation has seen Chloe Swarbrick and Golriz Ghahraman move up to seventh and eighth, respectively, on the Green Party list.
Mr Shaw has called it his "Turning the Tide" speech.
"We have got the fight of our lives on our hands."
A new female co-leader would not be appointed until the party's AGM next year, with Mr Shaw leading the party alone until then.
