There is no reason why there should not be another referendum on rejoining Europe.
The role of whips has absolutely nothing to do with whether there should be another referendum on Europe.
I know as much as you do about UK politics,I lived in the uk from 1951 t0 1990
Anybody that states that the uk is not set up for referendums[is clearly ill informed when there have been 3 since.1975 two of them concerning respectively the common market and the second leaving Europe.
You may not like the result of the last referendum [neither do I], but they happen and can happen again, here is some info
The Government of the United Kingdom has also to date held ten major referendums within the constituent countries of England, Scotland, Wales and Northern Ireland on issues of devolution, sovereignty and independence; the first such referendum was the 1973 Northern Ireland border poll and, as of 2023, the most recent is the 2014 Scottish independence referendum.