Here is a couple of other translations of this text that you might want to consider.
So that we henceforth have known no one according to the flesh, and even if we have known Christ according to the flesh, yet now we know him no more; YLT
So that we, from now on, are acquainted with no one according to flesh. Yet even if we have known Christ according to flesh, nevertheless now we know Him so no longer. TCV
Some help may come from the context.
[font="'Times New Roman"]14 For the love of Christ is constraining us, judging this, that, if One died for the sake of all, consequently all died.
15 And He died for the sake of all that those who are living should by no means still be living to themselves, but to the One dying and being roused for their sakes.
16 So that we, from now on, are acquainted with no one according to flesh. Yet even if we have known Christ according to flesh, nevertheless now we know Him so no longer.
17 So that, if anyone is in Christ, there is a new creation: the primitive passed by. Lo! there has come new!
18 Yet all is of God, Who conciliates us to Himself through Christ, and is giving us the dispensation of the conciliation,
19 how that God was in Christ, conciliating the world to Himself, not reckoning their offenses to them, and placing in us the word of the conciliation.[/font]