If you do not nip this in the bud NOW, you are in for it! The only way that any discipline will work is if you implement it at the FIRST sign of the misbehavior or the disrespect..... SO, at the first indication of this ATTITUDE,
say firmly, "You are NOT to speak to us in that way!" or " That behavior is disrespectful " or "Spitting is not acceptable behavior!) and then you take her immediately to the time out spot (a completely boring spot that has nothing in or around it to distract her), and she must stay there for 5 minutes. If she gets up, take her back and reset the timer, as many times as necessary until she gets the idea that you are not kidding....no talking or arguing allowed! At the end of the time, remind her why she was there, then she must apologize, give her a hug, and then she may get up.If she will not cooperate, reset the timer! It will take you doing this EVERY SINGLE time she shows this attitude, for you to get through to her that such behavior will NOT be tolerated in your home/family.
Start NOW unless you want the next 13 years to be hell! Also, read books by Dr. John Rosemond for help, watch SUPERNANNY, and read NOBODY SAID IT WOULD BE EASY by Dan Kiley. AND, your 3 year old can spend 3 minutes in a time out spot if necessary, and it works the same way for her.
Updated
I forgot to say that you might want to think about where she is getting such ideas from,,,,playmates, TV shows etc. and monitor her more closely. Do not hesitate to cut off any undesirable influences that might be fueling her disrespectful behavior and language.