Second coat of Quikrete High Performance Self-Leveling Resurfacer
The OP added this in a comment:


  I never heard back from Quikrete from the email support request so
  called the customer support number and the guy was very helpful. 
  
  Answer: Yes. Multiple coats can be applied. Restrictions - wait 24
  hours. Pour additional applications up to 1". 
  
  I was envisioning the stuff freely flowing all over the floor like
  water, but it's cement. Mistakes I made: 
  
  
  Not having maximum amount pre-mixed and ready to pour (literally) at once. 
  Underestimating amount of material I needed. 
  Trying to smooth it with a floor squeegee. Don't touch it! 
  A bit too thick