Please read the rules and refrain from posting your email address. As for your question, I do not see a way to do that. When LVM was designed they do not consider that an existing disk might grow somehow. You would need to remove the physical volume from the volume group, redo the pvcreate, and then add the PV back in to the VG. This would mean that you would lose all data on the disk. When you add disk space, you really want to make it appear that a new disk drive was installed. Then you can just add the new space into the VG.
1.- backaup everything on the VG, delete the VG and the PV, recreate it and restore the data, but this is time consuming, and let the system down for a lot of time
2.- use the undocument command vgmodify, but this command do not came with the regular operating system (HP-UX 11.11), and I don't know where to download it.
Interesting! vgmodify can do this and it is included with the most recent HP-UX version. It also seems to be in patch PHCO_35524, but that is for HP-UX 11.23. Try to get the lastest LVM commands patch for your OS and see if vgmodify is there.
I use vgmodify, but there is a new error message sayng that vg can't address more than 1 TB. So it seem that I will need to backup everything, and made and smaller LUN