At this time none of the aviation companies offer automatic renewals on any aviation policies.
One biggest reason is there is not a standard recording system for pilots. Automotive insurance is not generally based on how may hours you drive the car, but on your driving record (which is recorded and accessible through a motor vehicle record search).
Aviation requires updates of how many hours you fly and if you have had any accidents and violations. Since there is not a central location to gather that information for all pilots, they do not automatically renew. The insured has to provide the updated information every year. It is a very labor intensive process from our end and kind of a pain for the insured...
Hope that helps.