I
actually had a NPPL which I uprated to PPL a number of years ago
As I understand it,your NPPL lasts for life so should still be valid (if your medical is also.)Your recent rating (SEP?) should I think carry over to the NPPL.
Thinking of doing a similar thing myself when my SEP expires end of next year.
I don't fly abroad these days ( and that could change with the NPPL,Channel Islands now available),will use my NQ very little,no plans for IMC so can see little point in a JAA licence for me.
For me,I enjoy the flying itself,destinations are secondary.
Try to keep your feet off the ground a little longer if you can.
MM