Why won't my webGl page load a second time after a refresh?

This is a JS page my friend and I are making. http://ift.tt/1DSlZLO

The page loads fine when you first open it in a tab (albeit a little slow), but when you refresh the tab, the WebGl canvas will just be completely blank. The HTML elements are displayed though. We're using Three.js. Are there browser compatibility issues with WebGL that could be related? Is something being cached and causing an issue?

Any idea? Thanks!