After his opening address he told media that he wanted a war chest "way beyond" $1 million to fight the next election, and said he would resign if membership didn't grow to support that.
NZ First spent $268,530 on last year's election campaign.
Asked if he would he resign if membership did not grow by tens of thousands of people, he said he would, before later backing away from that and saying he misheard the question.
"If we get our party's organisation and its membership and fundraising right, we will be in a three way fight. The idea that this is between National and Labour is all wrong - our growth and our support tells us we have every chance in the next election."
Mr Peters said he wanted to get much more than 15 MPs into Parliament after the next election. The party currently has 12 MPs.
"The days of us not going for broke are over...that's what this convention is about."
He rejected the title of kingmaker, but said NZ First would be in a position to decide the next election: "That's our plan. We have done it twice in our past."
Green co-leader James Shaw responded to Mr Peters' comments about the next election being a three way fight with a tweet saying, "Dreams are free".
Mr Peters said those who believed the Greens would realistically be in a position to have any real influence come 2017 were mistaken.
"James has been in the game for five seconds...if your mathematics gets them to being a majority, you tell me how it does...I can do the mathematics, I have been in situations of forming a government twice, and missing out on doing that by only one seat three other times.
"Now, what's the Greens' record? Not getting within cooey of doing it."
Mr Peters said the Greens had ensured the "unlosable election" was lost last year, returning National to power.
"The Greens came out and attacked the Labour Party four times in the last election."
Despite that, he would not rule out forming a coalition with the Greens in future.
Mr Peters said he expected much of the extra money to come from the increase in membership, but would also be open to donations from business - although he said NZ First would not take donations from people such as Donghua Liu, who "corrupted the process".
"People want to help us. We just have not perfected the mechanism to get them to do it."
Mr Peters, who has said he will continue past the 2017 election, batted away questions about a succession plan.
"Yeah, I do [have a plan], there are about 11 [MPs] in caucus now."
Asked about former Labour MP Shane Jones - who is widely rumoured to be a leader-in-waiting - Mr Peters said he had a lot of respect for him.
"There are a lot of people who are looking hard at NZ First now, in terms of supporting it...I can't answer for Shane, I've got a lot of respect for Shane, as you know, being highly supportive of him in the past. And he is a highly intelligent guy."
The conference room in Rotorua has been bedecked with 25 New Zealand flags - underlining the party's strong opposition to changing the flag and the associated cost.
The morning began with the national anthem. Mr Peters said earlier this week was a "funereal dirge", and failed the test of whether people sang it when they were happy - "I've never heard anyone singing our anthem when they're happy".
He later issued a statement saying it was a personal opinion and not NZ First policy to change the anthem, and today sang the words under his breath and looking down.
After his opening address he told media that he wanted a war chest "way beyond" $1 million to fight the next election, and said he would resign if membership didn't grow to support that.
NZ First spent $268,530 on last year's election campaign. Asked if he would he resign if membership did not grow by tens of thousands of people, he said he would, before later backing away from that and saying he misheard the question.
