Do you have a sediment issue? One concern with filters prior to the softener is the filter reducing the flow rate to the softener so the softener cannot regenerate properly.
If you do have a sediment issue, recommend a sediment filter that will not tend to restrict flow and is easily cleanable such as the Lakos Twist2Clean:
http://www.twistiiclean.com/
Now that your flow has been restored by changing the filter cartridge, you could add a few extra gallons water to the softener's brine tank, wait 2 hours for additional salt to dissolve, and then initiate a manual regeneration cycle. If you do this while you are available, you can then observe to ensure the various cycles of regeneration do actually occur.