Set Automatic Value For Date?

You might be able to use the free of charge Compliance Kit, Configuration Accelerators add-on, in particular the Managed Properties module, Auto Calculated Property feature.
You can configure it to set a dynamic value in your property depending on other metadata, current date etc.
Not 100% certain that you can actually add a year to current date, but I don't see why it should not be possible.
Alternatively you could create a separate assignment in your workflow to work as a reminder with deadline one year ahead. The downside of that is that this assignment will show up in lists during the long waiting period.
I prefer to create a separate Task-object with a workflow that keeps it waiting silently until a specified notify date is reached. At that time a new assignment is created by the workflow. But this approach also requires some scripting if you want things to be automated...!

You might be able to use the free of charge Compliance Kit, Configuration Accelerators add-on, in particular the Managed Properties module, Auto Calculated Property feature.
You can configure it to set a dynamic value in your property depending on other metadata, current date etc.
Not 100% certain that you can actually add a year to current date, but I don't see why it should not be possible.
Alternatively you could create a separate assignment in your workflow to work as a reminder with deadline one year ahead. The downside of that is that this assignment will show up in lists during the long waiting period.
I prefer to create a separate Task-object with a workflow that keeps it waiting silently until a specified notify date is reached. At that time a new assignment is created by the workflow. But this approach also requires some scripting if you want things to be automated...!