Appending data to a json file

[Dave]

I created a python program that gets data from a user, stores the data 
as a dictionary in a list of dictionaries.  When the program quits, it 
saves the data file.  My desire is to append the new data to the 
existing data file as is done with purely text files.  However, I can't 
find a way to do that.  The advice I have seen on the web is to load the 
data when the program starts, append the new user input to the list, 
then re-write the data file.  Is that the best way, or is there a better 
way?

Thanks,
Dave