Have menus update when new content is created

Im looking for a plugin or some way that I can have my menu have the word new show up next to the menu item when a new page is posted. The website im building is a knowledge based site for our tech support team. When new information is posted I’d like the word new to show up for 7 days in the drop down menu all the way down the tree until it gets to the end of the tree. Does a plugin for this already exist?