A referendum on whether NI should stay in the UK or join the Republic.
Ah right I get it!
Now I understand that question I'm still at a loss to know why that has anything to do with my suggestions on how our constitution should be reformed as that would not be a matter for the UK?
(The UK has no legal way of forcing its will on another country so the only way such a poll could come into being would be after "NI" had left the UK. At that point it is up to the new NI country to decide what it wants to do, what negotiations it wants to enter into with other countries and so on.)