Detect if file-header exist & update

[PezCoder]

After looking for so long, found this which actually worked like how I wanted it to work. So thank you.!

Context

I'm using this to define a copyright statement & add it when launching :Header vim command

Question

Just one concern is that, I want to run :Header in some autocmd for certain file types & probably prewrite.
But on multiple runs of these commands keep adding the copyright header.

This may be more like a VIM question, but is there a way to detect the pattern that was specified to copyright & not add it, rather update/replace it in case it exists already?