Before adding the new Data to your Dataset you should add a column that can be used to filter the data so it will score only the desired data. (Example add a column called "Score" which is a Boolean Data Type column 0 = exclude, 1 = include).
Then you could add new Data to you Dataset
For the already used Data to train and generate the Model the values of "Score" in all rows would be 0. However for the newly added Data to the Dataset the values of "Score" in all rows would be 1.
Then when running the Scoring Job use the Filter on column Score with 1= include.
I hope this helps.