She literally can't, physically or mentally.
If she admits to being wrong once, her entire brand is destroyed.
She literally has, about an hour after she said it.
The Washington Post gave this story zero pinocchios after she corrected the error. (Sorry. No link. Interested parties will have to find via google.)
I assume you mean this page? It says:
Uncorrected, this would have been worth Four Pinocchios. But Conway says it’s an “honest mistake.” We appreciate that she sought to correct the record. Readers can judge for themselves, but as we don’t play gotcha, we will leave this unrated.
Personally, I don't buy the "honest mistake". Kellyanne is the Orange Führer's primary spokesperson, and the immigration ban one of his most controversial decisions - not just in hindsight, you could predict that.
Let's look at what she precisely said (copied from
wiki):
I bet, there was very little coverage — I bet it's brand new information to people that President Obama had a six-month ban on the Iraqi refugee program after two Iraqis came here to this country, were radicalized — and they were the masterminds behind the Bowling Green massacre. I mean, most people don't know that because it didn't get covered.
She added another sentence to it, but I can't make out what she said.
There's a load of falsehoods in that statement.
1) Obama did not institute a six-month ban. He upped the vetting on Iraqi refugees, but every subsequent month, Iraqi refugees were admitted. On top of that, the intent of this statement is to equivocate it with Trump's ban, which is much wider in scope both in nationalities and in types of visas.
2) The two terrorists in question were not radicalized while in the USA; they had already committed terrorist actions while in Iraq and posed successfully as refugees. This falsehood actually makes no sense, as trying to discern who will become radicalized is like reading tea leaves.
3) There was no massacre in Bowling Green. The two terrorists didn't either plan to commit a massacre themselves.
4) They didn't even manage to get their contraband out of the USA.
5) All of that was widely reported at the time. For the stricter vetting, and not ban, see
this WaPo fact checker.
Lastly, I don't think that Kellyanne deserves any leniency. She has been Trump's mouthpiece for, what, the last half year, and has been continually peddling lies, or, as she prefers to call them, "alternative facts". When she says it's raining, I look out the window to check it. The baseline for any utterance of her should be four pinocchios.