What would be the source to update / refresh partion backups ?
I do not exactly know a GUI tool but in the end this could boil down to mounting a dd image file via loop back option (similar to an ISO), apply the changes from the source to the dump via rsync and then unmount the dd image.
I am not aware of any backup solution which allows to do incremental backups to a full dump.
Depending on your knowledge I would go for Python and some toolkit (e.g. GTK) or may be Gambas / Lazarus plus some shell commands. Gambas if you are more the Basic kind of guy or Lazarus if you worked with Delpi / Opbject pascal so far.
It is really easiy to hack together a simplistic GUI in the form editors today.
