All the indications are that a second in/out referendum would result in Remain by margin of at least 8%. That's over double the margin the other way last time and whatever the government they'd be obliged to honour that more decisive 12% swing vote, an unusually high swing in any election.
I don't think many leavers wíll have changed their minds, the difference now is for other reasons. Last time, just like Cameron, many were complacent in their belief that Remain would win so didn't bother to vote and as a result had a shock at the result.
They wouldn't make that mistake again so the Remain turnout would be very much larger and more determined. Add to that the minority of Leavers who are fed up with the whole issue so might not vote again and you get a big voting swing. The margin could even be over 10%, a 14% + swing.
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