How do I tell Internet Explorer in Windows Phone 8 to refresh the page by sending new request to server and not displaying data from cache (hard refresh)? Something like pressing CTRL-F5 in a PC browser.
Unfortunately, there is no direct way (yet) to do what you are trying to.
However, an indirect way of doing this is to clear your cache by following the instructions here.
Alternatively, you could consider using a browser other than Internet Explorer and try and make feature requests for these. Here is a discussion about alternative browsers on Windows Phone.