Depending on your requirements or reasons to migrate to WPF, you could simply host a WinForms control (for example, a UserConrol-derived class, or Panel-derived class, with custom GDI+ painting) in a WPF window - which will enable you to have a WPF application, but to draw your game in a Windows Forms environment.

See this article: Walkthrough: Hosting a Windows Forms Control in WPF