It's always a gamble. The more confident you are that your score will improve, and the greater the expected improvement, the better a bet it is for you. No one here, however, can make those judgements for you. If, for example, you were practicing in the mid-170s but weren't feeling well on the day of the test, I would think a retake is worthwhile. If, on the other hand, your best practice score was 169, then I would say that those three points are not worth the risk.