Speaking to German newspaper Welt am Sonntag, Mrs Merkel said: "I'd make all the important decisions of 2015 the same way again".
Four weeks before the September 24 election, an Emnid opinion poll on Sunday showed Merkel's conservatives would win 38 percent, or 15 points ahead of the center-left Social Democrats (SPD).
"I think that we're in a much better position today than we were a year ago, when I was a lot more anxious and I wish Greece every success", Merkel said.
"I made my decision based on what I thought was right from a political and humanitarian standpoint".
"In spite of that, it is necessary to continue negotiations on the possibility of a [political] transition that would facilitate reconciliation", Merkel stated. The farthest Merkel would go in that direction, however, was to say she could support a eurozone "economy and finance minister" focused on improving the currency area's competitiveness.
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"Either we [in Europe] show solidarity with countries like Italy and Greece or this will have grave impact in the future", she said.
Opposition has been particularly staunch in her home region in former communist east Germany.
She also placed the blame ironically on the border restrictions already in place - prior to the autumn of 2015 - to check the unregulated inflow of the refugees into Europe. This centre would be in Egypt, a transit country for migrants striving to reach Europe.
"This requires patience with people's concerns and the attempt to address them repeatedly with concrete solutions to specific problems", said Merkel, who is also the candidate of the ruling Christian Democratic Union (CDU) for the next chancellery. Mr Schulz, who doesn't have a position in Ms Merkel's administration, has said it's the government's job to avoid driving bans.
Supporters of the far-right, anti-immigrant Alternative for Germany (AfD) party jeered her throughout a 30-minute campaign speech in the eastern city of Bitterfeld-Wolfen hours after Merkel declared comments by a top AfD official to be racist.
However, she admitted that European Union law at the time had been inadequate for dealing with the enormous refugee influx that ensued.