[CentOS] Freeing pv space for snapshots

After upgrading my HD, I am now wishing I left some space for doing
snapshots.  Is there a way to free up some space so I can get some free
PE?

Right now I have this:
# vgdisplay
  --- Volume group ---
  VG Name               VolGroup00
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  7
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               38.22 GB
  PE Size               32.00 MB
  Total PE              1223
  Alloc PE / Size       1223 / 38.22 GB
  Free  PE / Size       0 / 0
  VG UUID               0mB18U-4VRo-1GMC-oKdf-ZndA-slFy-eOQtYD

So, it won't let me do this:
# lvcreate -L1G -s -n fullbakup /dev/VolGroup00/LogVol00
  Insufficient free extents (0) in volume group VolGroup00: 32 required

Ext2online will not reduce size, so the man page says and I also tried it
for the fun of it.

lvresize won't work either.