I recently parted ways with my book cover designer (amicably), and he was gracious enough to give me a free ebook cover that he'd already produced last year but hadn't sent to me. However, it was only in ebook format, and my books are both ebook and paperback.
In case you've never heard of myecovermaker.com it's a site that offers both free and paid ecover design options.
Simply select your ebook cover to upload using the full paperback template (it will be watermarked until you pay the $4.95USD at the end-just fyi...it is free only for ebook covers, but it sure beats having to pay full pop for a whole new cover)
After you have uploaded your image, simply drag it so it fits inside the front matter parameters. Then add in your back cover matter and spine.
Tip: make sure there is a full finger-width of space between the outer edges on all four sides of your cover so you don't have any bleeding over.
Once you are happy with the look of it, it will prompt you to pay the $4.95USD and then the watermark is removed and you can upload your design on to either Createspace or whatever paperback publisher you are using.
Hint: You will need to convert the cover to pdf format (it is downloaded to you in jpeg from myecovermaker.com) before uploading to Createspace.com.
I did this with my latest book cover and it looks great. Updating your book cover and blurb periodically (especially if you notice a dip in sales) is a great way to bring new interest to your work