Florida has laws against trespassing - see Chapter 810. The first step is to notify the offender that her presence is unwanted and further incursions onto your land will be deemed a trespass and acted on accordingly.
This is done by what is, in my area, called a Letter Of Disinvite, specifically informing the recipient that they are not to come onto the sender's property. It should be sent by Certified Mail/Return Receipt Requested; a copy is commonly sent to the police so that they know a trespass has occurred if the recipient is subsequently found on the sender's land.
You may wish to consult an attorney to make sure the procedure under Florida law is properly followed.