Shoot that sucker with the garden hose and yell like a banshee every time it comes near.
This was an issue at my house when I first moved in (along with neighbor kids wandering over) but I fenced in my backyard I don't know what I would do if it was a front yard issue as well. My neighbor's child still wanders over during the day especially in the summer when school is out. I'm afraid licensing is going to get me for that but what can I do? His family has a history of mental illness and I don't want to put myself anywhere in the vicinity of their radar. If I ever did have a real front yard issue I'd probably fence that in too. Right now he listens when I tell him he needs to go home and leave the kids here be. Maybe there's a repellent of some kind you can use along the fence line to keep the dog back?