"We have not been offering good positive alternatives and what I want us to do is to paint a vision of a 21st Century relationship between Britain and our European neighbours.''
The UKIP leader has attempted to broaden the party's appeal from that of a single issue group.
But he is still expected to focus on its opposition to the Lisbon Treaty in next May's polls - contrasting his party's position with that of David Cameron's Conservatives.
In his keynote speech, Mr Farage said: "David Cameron could kill the Lisbon Treaty stone dead.
"All he has to do is say that there will be a referendum on the treaty after the next election when - and let's not kid ourselves on this - he will be prime minister.
"This would strengthen the arms of the Polish and Czech presidents in their refusals to ratify Lisbon and make any attempt at a second referendum in Ireland impossible."
Mr Farage added: "Everyone knows that the Constitution - sorry, the Lisbon Treaty - will never be approved by the British people, which is why we've not been asked about it.
"So if Cameron were as Eurosceptic as he claims, he would do this. He could stand up this afternoon and announce a retrospective referendum.
"So the question has to be, why doesn't he do this? Is he not as Eurosceptic as he claims?"
The Tories pledged in January to hold a referendum on the Lisbon Treaty if they won power before it was ratified by all 27 EU states.
But they did not explain whether they would attempt to reopen negotiations on the Treaty if it had been ratified by every state.
'Friendly with Europe'
Gordon Brown said last year that a referendum on the treaty was not necessary because most changes were minor or procedural.
UKIP achieved a breakthrough at the most recent European elections, in 2004, when it gained 2.7 million votes, or 16% of the vote, pushing the Liberal Democrats into fourth place.
It has fared poorly in subsequent polls, gaining less than 1% of the vote in the recent London mayoral elections.
But Mr Farage believes the proportional representation system used in the European elections gave it a good chance of building on its 2004 success.
He told delegates: ''In the European elections of 2009, we are going to be on every single ballot paper in the United Kingdom, and we are the party of opposition.
"We are the party that says we want to trade with Europe, we want to be friendly with Europe, but we insist that we should make our own laws in this country because the best people to govern Britain are the British people themselves.''
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