Its not as simple as reversing every long signal to a short signal or vice versa. Just because one strategy has no edge it doesn't automatically mean the opposite does, both could be successful on a random basis - which means bankruptcy in the long term.
Also, if your wins depend on price following a trend, and the uptrend is not sufficiently strong, that doesn't mean there is a downtrend in place. If your wins depend on an upward break-out from a range, the failure of the bullish break-out doesn't mean there is a bearish break-out now in progress or even imminent.
However, there are elements of converse thinking that could be helpful. If you are buying after prices rise or at a new high or at the high close of a bar, it might be better to buy after prices fall, or after a new low or at the low close of a bar - whatever your entry pattern might indicate. You're still going in the same direction of course, but you might have shifted the probability of continuation in your favour, while also getting a discounted entry price.