Dear Sam,
as business requirement is,
to update the planned versions,it is not possible
versions are the snapshots and cannot be updated manually or by any means,
to do so every time you have to take a new version and get the approval for the same
any changes you make to the project can be compared with the already created version,so you can have a comparison of current data verses version data
once again i confirm that you cant change version or manually update it