Doubling your investment in a year is going to be tricky. The only two things I can think off are gambling or high-yield bitcoin p2p loans on platforms like Bitbond. Going to be tough though.
I don't know about bitbond, but the average apr of btcjam is 9% (with autoinvest on, not manual investing). It would take 8 years(!!!) of compounding interest to double $100,000. So... no. OP wants it done in a year.
I don't think that there is a good way to do it. If there was a safe way to double $100,000, wouldn't everybody do it?
I don't think you should discount bitcoin p2p lending so easily. This guy made 117% return within 12 months.
so it is possible. Will it be easy? No, definitely not.... but it can be done.