Tony Blair has said New Labour must be the party of the "change makers" if it is to secure its lasting legacy.
The prime minister told Labour's annual conference there must be further reforms to public services so choice is not just the preserve of the wealthy.
He said the criminal justice system needed reform - 21st Century crime was being fought with 19th Century methods.
Mr Blair's policy-laden speech was seen as signalling that he does not intend to step down early as prime minister.
In his keynote speech in Brighton, Mr Blair said he regretted not going further with his reforms over the past eight years but said that New Labour had still been the party of the "change-makers".
"And that's how we must stay," he said. "Then the fourth election can be won and the future will be ours to share."
Mr Blair said he wanted his party to make Britain at ease with globalisation, forge a new consensus on public services and respond to public anger about crime and anti-social behaviour.
The speech comes after Chancellor Gordon Brown delivered a speech on Monday seen as confirming his status as leader-in-waiting.
With leadership speculation dominating events at the conference, Mr Blair's task was trying to refocus attention on his plans and to show he had not run out of steam as prime minister.
Whatever the "noise" around the government, it had to persevere with the things that mattered to secure the future for Labour and the country, he argued.
Mr Blair said Labour had to modernise to win power in 1997 but the world had changed again.
"So now in turn, we have to change again," he said. "Not step back from New Labour but step up to a new mark a changing world is setting for us."
Mr Blair said New Labour had won the "battle of values" but had to renew itself yet again to secure the future.
Efforts to improve choice in public services, sometimes involving the private sector, have proved controversial with some Labour members and trade unionists.
But he warned: "For Labour, choice should be too important to be the monopoly of the wealthy."
Peace and democracy
After Mr Brown's speech on Monday delegates were looking for any sign of Mr Blair's future leadership intentions.
He did not announce a date for his retirement, which he says will be before the next election, but he heaped praise on Mr Brown's record as chancellor.
Ahead of his speech his wife Cherie laughed off suggestions she would soon miss her role as prime minister's wife, telling the BBC: "Darling that is a long way in the future. It is too far ahead for me to even think about."
And Home Secretary Charles Clarke told the BBC News he wanted Mr Blair to stay "right up to the end of the Parliament", which could be May 2010.
During his speech, Mr Blair also spoke of his pride in the way London had reacted to the tragedy of the bombings in July.
He spoke of the need to ensure peace and democracy is brought to Iraq, saying the fight against terrorism was at its fiercest there.
He said the terrorists were using 21st century means to fight a "pre-medieval religious war utterly alien to the future of humankind".
Despite the problems, eight-and-half million Iraqis had shown the direction they wanted when they turned out to vote in January's elections, said Mr Blair.
The way to stop the innocent dying was "to stand up for their right to elect their government in the same democratic way the British people do", he added.
Conservative chairman Francis Maude dismissed the speech, saying: "What people want from Mr Blair is not more polished rhetoric about the future but practical solutions to the problems of the present."
Lib Dem leader Charles Kennedy said: "What people want are quality schools and healthcare and safe streets. After eight years of Labour, they're still waiting."
Scottish National Party Alex Salmond said: "It was an underwhelming performance from a man with an eye on his own exit strategy, even if he stubbornly refuses to find one for our soldiers in Iraq."