The topic of incorporating external data sources has been discussed on Quantopian (e.g. see https://www.quantopian.com/posts/different-kinds-of-data-sources). Until more sophisticated tools become available, I suggested a brute-force copy-and-paste approach of the external data into the algorithm editor. I have not tried this yet, but I was advised that each algorithm can be up to 16 MB. So, unless there is lots of overhead, the technique should work for your algorithm above.
The daily VIX history can be downloaded from Yahoo finance (see http://finance.yahoo.com/q/hp?s=^VIX+Historical+Prices). Then, it's a matter of sorting out how to get it into a format that would be suitable for pasting into the algorithm. My inclination is to just put the data in a numpy array, but there is probably a better approach (I'll post a question).
Once we sort out the details, you should be able to re-run your algorithm with the actual, daily VIX data...I think.