Share 'Flea remedies'

Hi I rescued a Great Pyreness about a month ago. She has the run of 2 acres but is brought indoors at night. Lately I noticed the tell tale signs of fleas on her even though she is up to date on her Advantix. Really concerned with her coat and the thickness that it might not be effective enough. Was wondering if there were any herbal or any tell tale remedies that may work... I have heard a few h…