Yes it is possible to update SLDLFP files. What you want to update in them?
Run a Solidworks Task Scheduler if your just trying to update the version to a new installed version of solidworks.
You can do it via #TASK .
Just specify the filter for sldlfp and select 'Update and Save' task from the library:
If the files of an older version of SW and you want to upgrade them you need to make sure that this option is checked: