Here's a link to a great article on "5 Tips for Marketing Your Novel The Second Time Around" by Dan McGirt. It came via Dana Lynn Smith's regular Savvy Bookmarketer Newsletter--a free subscription you shouldn't be without.
I must admit I've been thinking about reviving a couple of my earlier novels, specifically Where Is Papa's Shining Star? and its sequel Finding Papa's Shining Star. I'm not looking to take them back from the publisher who has graciously extended my contract for these two books--which, I might add, haven't sold as well as I'd like. Rather, I'm looking for ways to make them "new" again and find the right audience. I know it's out there--readers who like the sentimental romance and a glimpse back into lives lived during the eras of the Great Depression and WW II.
Dan McGirt has some good food for thought in his 5 tips. I like the "Word of mouth still works" approach.
Meanwhile, if you aren't familiar with the above-mentioned books and like that approach to love and life, visit my website and watch the video trailer for each one, then read the first chapters.