Yes, thats an option or you can go to www.amigakit.com they sell new install floppy discs for OS 3.1 that has all the new files.
Ideally you want to do a clean install of the OS in order to do it right. You want to patch over to Either SFS or PFS as the harddrive format as well to eliminate issues caused by using FFS.
You can find many of these patches on aminet.net