Tasting blood has nothing to do with whether she will attack your lab again. That is a very old wive’s tale and not to be believed.
There are many questions that need to be answered, but even if they are, we cannot provide you with guidance online. Questions such as:
What are the ages of the dogs?
Did your lab provoke the pit?
Did the pit give off warning signals that were missed by you?
Was there resource guarding involved?
Was there food involved?
How long have they lived together?
Are they both altered?
Was there a “stare off”?
And the list could go on and on. My suggestion would be to contact a licensed trainer or behaviorist and take your pit to see him/her. They could put her through various temperament tests to see what may have triggered her to bite.
As I am sure you know, pit bulls can be dog-aggressive. That doesn’t apply to all, but that is a possibility that all pit owners need to take into consideration. Pits tend to be late in hitting maturity (between 2-4 years of age), so depending on the age of your pit, she could be hitting her maturity level and may be showing signs of dog aggression. I don’t know.
We can give you all the advice and theories that we want, but without seeing what is truly going on in the home, we cannot provide you much guidance other than to say keep them apart for awhile, re-socialize if necessary, and seek the professional help of a trainer/behaviorist.
Give your lab a hug from me! 🙂