How well do You like Your girlfriend?
I didnt know it ever got cold in Florida!
The best thing to do, would be relace it, but its a big pain.
May as well flush out the cooling system while Your at it. To see if any more are rusted out.
Anyway, it will only get worse.
If things are real serious between You 2, then pull the motor and replace ALL of them.
You could try one of those rubber plugs that expand when You tighten them...But You still have to get the old freeze plug out and clean up the hole so the new rubber one will seal properly.
Now...My idiot brother actually SWEARS by taking egg whites and adding them to your radiator and then starting the car up till its warmed up...
I asked him one time, do You add salt and pepper with that? He didnt think it was funny