I would write out the light values to a temp file , then you can read them back in later.

writing a file

myfile = "c:templightvalues.txt"
fo = file("myfile,"w")
for light in lights:
      write light.value + "n"

fo.close()
#reading a file
myfile = "c:templightvalues.txt"
fi = file(myfile,"r")
for line in fi :

set light to value from line

fi.close()