Best out of three, five, how many?
Actually the 2016 referendum was already the second with an almost identical question on whether or not to remain in the EU.
But you are missing the point - this isn't about having referendums until you get the right result. It is about being confident that what is actually proposed to be implemented has a mandate at the point when it is to be implemented.
And I'm consistent on this - the kinds of decision seen in the EU referendum and the Scottish indy ref cannot, in my view, be subject to a single referendum as, by definition at that time there is nowhere near enough clarity on what the detail looks like. So there should be a 2 stage process (and I said this years back in 2014 about the indyref). The first vote should provide a mandate to negotiate an agreement, in these cases on leaving the EU and on leaving the UK. Once that deal is agreed on both sides and is implementable the deal should be put back to the people to determine whether they still want to proceed with leaving the EU/UK on the basis of the agreed deal.
This isn't having referendum after referendum but putting the people in charge at the beginning and at the end of the process.
Surely you cannot be happy with a situation where we might leave the EU, later this year in a manner that doesn't have majority support of the people.