Retroactively Modifying Selected Business Card Template

[Cerin]

I'm trying to create some business cards for Avery 8869 stock (template 8371 for Word). Since Openoffice doesn't include a template for this, I created my own. It seemed to work ok until I printed out a sample with a full background image. I found the template dimensions were slightly off, so that the background image was slightly offset, progressively getting worse for each row on the stock. Now I need to readjust dimensions of the template, but I don't see any option to do that without starting from scratch.

How do I take an existing document and run it through the business card formatting wizard in order to re-adjust the dimensions?

Thanks,
Chris