Use
Space Sniffer to note down what exactly is using so much space and then do some jiggery pokery. Turning off System Restore, Hibernation and forcing the Pagefile to a fixed smaller size will saved many GB of space as well and is advised for SSD usage.
The sensible and ideal solution is to never keep personal documents and media on the OS drive, always keep it on another drive just for data storage. Windows 7 is super easy when it comes to mapping the media/doc folders to another location so if you have another HDD kicking around then do that first. That will free up a lot of space.
Secondly, if you have large games then bung them on another drive as well, while some games load faster off an SSD the difference isn't that huge compared to the absolutely massive difference in OS and software software performance within Windows and booting up. You can use Symlinks in STEAM to move installed games to another drive and STEAM will see them via symlinks easily
Keep the OS drive managed and maintain it regularly and your OS should never need a "fresh" install because it will always be fresh