Of the thirteen books nominated to the 2011 Booker Prize longlist, every single one involved the theme of death.
How many of your favorite novels involve a death? How many of your own stories? We've heard it said that we authors need to kill our darlings. The gist of that expression is that we develop an emotional attachment to our very clever work, which then colors our judgment. But maybe we need to be a little more literal and actual whack a character or two. It may be that a little authorial murder is just what you need to publish your work!