You can do it this way: 1. export all of your data to a gedcom file 2. create a new PAF file with a new name 3. import the gedcom file
This will allow PAF to renumber the RINs so that there are no unused RINs. If it changes your own RIN (this is highly unlikely), you can use the Tools menu > Preferences > File to select your RIN as the person shown when the file is opened.
Let us know how it worked. If it worked perfectly (as it should), the new PAF file will become your main file and the other one can be archived.