There is a limit of six search portlets that can be added to the Dashboard page.
However, you can include links to your saved searches within a shortcut portlet—though please note that only one shortcut portlet can be displayed at a time.
If you need to display more saved searches, one option is to create a custom center tab where you can add additional portlets. There is no limit to the number of search or shortcut portlets you can add within a custom center tab.