Dean, once you have restored the replica VM, you can edit the replica job for this VM and enable "replica seeding" in the first step. A new step called "Seeding will appear" later in the wizard, here you can select "replica mapping" and point the source VM to the restore replica VM by editing the mapping. This should avoid the complete initial replica and allow for a delta replica.
EMEA Cloud Architect @ Veeam Software
Veeam VMCE #1