You may use following tools, they can work in all kind of ASP.NET applications.
Resource Refactoring Tool, available at:http://resourcerefactoring.codeplex.com/
], it will extract hard coded strings from the code to resource files.
after extraction, you can use Zeta Resource Editor, available at:http://zetaresourceeditor.codeplex.com/
], it enables you to edit string resources from multiple different resource files together inside one single data grid.