I've always associated heaven with the spirit world in general. Heaven isn't a physical place like the earth is. But whilst in heaven satan and a whole multitude of angels rebelled. And these ones are now destined for the fiery gehenna - in other words these ones will be destroyed, in other words, they will die. But they are spirit and live in the spirit realm. So there must be death in the spirit realm.
Now, I was always told that Jehovah is currently allowing all sorts of governments to rule over mankind to prove to not only us but also to all the angles that no government but Jehovahs can affectively rule over the earth. When he does away with them at armageddon he will then place his kingdom on the earth. From that time onwards he would never again allow his rule to be questioned as he would now have proved his full right to rule. So should anyone turn away from jehovah in paradise that one would be struck down immediately. So what would happen if an angel in heaven should once again behave like satan and his demons? Would jehovah let him behave rebelliously or will he kill him?
The understanding i was led to believe that after paradise comes anyone who goes against jehovah, e8ther on earth or in heaven, would immediatelt be destroyed, killed, taste death. So to say that there isnt death in heaven, or ever would be, seems to be an illogical conclusions. The scriptures also do not explicitly say that death does or does not occur in heaven so teach dogmatically either way goes beyond scripture.
Personally i believe, when it says no more death, that this was given to mankind. So to me it is referring to the earthly, natural death that everyone ultimately experiences - which we experience because of adamic death if you believe in that. I belive this is the death that would be done away with. But if someone rebels against god again then god wouldnt allow so a thing to continue again so death would have to take place.
Of course everything ive just said could be completely wrong. Its just my own thoughts which continue to change based on my own understanding, experience and ignorance.