The problem is that there aren`t any php-scripts (or php dir) within the bin directory
in the eZ 3.1 version.
Is it possible to use the php-scripts from another ez-version? (Webserver is running on Windows)
I wouldnt recomment it because those scripts use new features.
However, you could delete the contents of var/cache and still use a spider tool like httrack,wget or others to rebuild the cache for you. Use cron to automate this. Im not sure if cron is on windows, doesnt it use the 'at' feature...?