That's not how democracy works. If there is a referendum, and you don't like the result, you don't just do a second referendum.
If you'd do that, you could achieve any result you want, just by doing it over and over until. Due to voter's fatigue and/or daily sentiment, results will vary, so you can pick a result by deciding when to stop.
It might make sense (though still be questionable) to repeat the vote if major facts changed, but I don't see that happening. The stock market shouldn't have been a big surprise, Cameron's resignation neither, nor the Leave faction retracting some of their promises.
As much as I don't like the outcome of the first referendum, I think it would be fundamentally undemocratic to do a second referendum.