We will hold the referendum as soon as you fulfill the first condition for that. Do you even know what that is? The united nations clearly spelt that out. The first step is Pakistan's withdrawal from Pakistani Kashmir. Do that, and then talk about referendum.
And by the way, the notion of a referendum is now outdated, because Pakistan pumped in non Kashmiri Pakistanis (Punjabis, sindhis etc) into Kashmir all these years. Send them all back and then talk about a referendum.
As opposed to that, India gave special privileges to kashmiris, that no non Kashmiri can settle in Indian Kashmir. Other than the horrible exodus of Kashmiri pundits by Islamic militants, no ethnic changes happened in Indian Kashmir. So if a referendum is held across Kashmir today, in Pakistani Kashmir it will be Punjabis and sindhis voting, not kashmiris. We kept our promise to kashmiris, you didn't.
If you want referendum, fulfill the first condition - withdraw all Pakistani forces from Pakistani Kashmir, and hold a referendum under UN mandate. What are you so afraid of, why aren't you doing it?