Well, it's a magic lasso, so presumably you've got a magic to-hit bonus when using it. Failing that, use it in a snare or trap of some kind.
An interesting side effect of "turn the lasso against her" is that it's much less reliable - indeed, probably useless - if WW [i]hasn't[/i] gone rogue. When WW is her own self doin good like she does, the lasso is [i]hers[/i] in a really fundamental way (until Genocide, neither Batman nor anyone else, except possibly Diana and the Greek gods, had any reason to believe anyone could turn the lasso against genuine Diana). After the badguy inevitably gets the plans and puts them into effect, WW gets to be the failure point - the plan against her fails because it's the only one that relies for its efficacy on the assumption that she has somehow gone rogue, and then Batman shows up with exposition and they go save the rest of the league. Even better, Batman gets to not be stupid: he does have a contingency against misuse of his contingencies, built right into one of the contingencies!
This turns the weakest part of the plot into a very strong point - you would get to say that even in his darkest, most bat-paranoid moments, Bruce still fundamentally trusts Diana (in his idiosyncratic way), and to do it in a way that makes him look rather clever.