Mine trie to figure out a strategy itself an d it found really good strategies... that only worked for old data. It was good at hindsight, rubbish at foresight. Maybe it needed tweaking.
This problem is known as overfitting. The solution is to add noise to the data. Create 10 copies of the data with random permutations to train it on.
So your solution would be to copy the data and add various noise... how would this noise be added, random changes in the prices? What should the spread and distribution in the randomness be?
I guess using more data and perhaps testing for consistency would help also.