Some need to take a fair wack of Tofranil to get a good result. I was on 300-350mg for several years. It worked great. But I wouldn't recommend that in your situation.
It is definitely worth a shot. But, given you've had success with SNRIs in the past, also consider sertraline. If necessary it is possible to supplement it with nortriptyline (Pamelor), a noradrenaline/norepinephrine reuptake inhibiting antidepressant, to essentially create a bespoke SNRI. This gets too complicated with Lexapro because of drug-drug interactions and concerns about the impact on the electrical system of the heart.
I'd like to give you a definitive answer, but there is no way of knowing whether it will be more effective at 400mg other than trying it. Sorry.