All you need to do is set up the VBScript to take the form data and store it in a text file.
The only "difference" is that you get the name of the text file from a function that includes the date.
Code:
TextFileName = "Data" & Format(Date,"yyyy-mm-dd") & ".dat"
So this way, because you set the open status of the text file to be append/create it will automatically write to the same file appending the data until the "Date" function returns a different date at which time it will automatically create a new file with the new filename and continue.