This question already has an answer here:
This question is different from Why doesn't the UK hold a second Brexit referendum to clarify what the public wants from Brexit? because that question is asking about voting on the form that Brexit would take, not checking if Britain actually wants Brexit or not.
An article from The Economist says that support for Brexit had dropped to below 50% by mid 2018 (45% Remain, 41% Leave). This gap is larger than the gap when Leave won the referendum. Interestingly, the graph shows support had returned to the same levels as 10 months before the referendum. It also appears that something in the campaigning was driving the Leave vote one or two months before the Referendum, and has since lost its influence, indicating that the Leave vote might have been artificially inflated by campaigning and not representative of what the public wants.
I know this graph doesn't show the data from the last nine months, but if the British people are no longer for Brexit (and maybe never truly wanted it), wouldn't it make sense to find out for sure and cancel Brexit?