I'm not COMPLETELY sure about this, but if you make an If/Else statement doing
if "frog" is "0.01" meters within "lake/water (whatever it is)"
Do "world.restart" (world.restart being a variable)
Else do nothing.
"world.restart" would be the frog restarting to the rock. So what you would do is create what is a called a "dummy object" (These, my friend, are life savers.) and place the dummy object on the rock. Have "world.restart" do this:
"frog" move to "dummy". I'm sorry if you aren't understanding what I am saying, and a link to making and using dummy objects is "
http://www.youtube.com/watch?v=2qHg7HoV19w "
Sorry if you didn't understand me, and if you didn't I hope the video helps!
~Okyloky9