Migz is correct, a project file is the way to save models.
If you input file is a database your users could change the source file quite simply.
If it is a "report" just close the previous file that has been saved and pre-loaded then open the new one. Or open the new one and close the previous one.
Unless you are doing something with the report name that cannot be achieved any other way you could also consider having a fixed substitute name and location for the file, known to the project, and copy the daily file to that name and location, overwriting the contents with a fresh file each day and saving the true original somewhere safe.
No doubt others will pop pup with their own suggestions for Project best practice - there are options.
If you have automation available you could go further with making the users lives simpler still.
There are plenty of good things to embrace with the project concept and minimal effort to deliver them.