Has anyone successfully converted a softcover project to a hardcover without having to regenerate it from scratch?
What adjustments were necessary (particularly with the cover)?
Yes, Yes, just did it two minutes ago.
Take your full cover jpeg in Photoshop. Resize by .5. so to fit the template you will have downloaded from lulu with the white outline for Casewrap. Mine was 13 inches. I made it 13.5 in width. The height was proportionately adjusted automatically.
White the barcode square. Paste your new barcode on it. Flatten image. Convert to PDF. Upload.
It's really pretty easy. Ask if you get stuck.
Attaching my template so you can see what I mean.
Now, how to get a template for Casewrap. Generate a fake one with lulu plain colours, download it and use that. You must have uploaded your new interior PDF with new ISBN to reach the cover stage again. Use old cover designer option.
I have done it several times.
Don't forget you need to get a new ISBN, and to enter it in the copyright page.