To find out how many more milliliters Kira's dog drank today compared to yesterday, we need to subtract the amount of water it drank yesterday from the amount it drank today.
Yesterday, the dog drank 739 milliliters, and today it drank 1006.7 milliliters.
The calculation is as follows:
\[ 1006.7 , \text{milliliters} - 739 , \text{milliliters} = 267.7 , \text{milliliters} \]
Therefore, the dog drank 267.7 milliliters more today than yesterday.