I had the same problem! However I found that if you turn off the lattice modifier (don't delete just turn off) and any scale restraints, unlock the all the eye scales - then select everything and scale to the size you need. Having re-scaled you will need to adjust a few things to the new scale. Some of the restraints max/min will need to be adjusted and you might need to double check that the dilation/constriction driver is still functioning correctly (if not you might have to re-do the driver, but it takes less time that completely remaking the eye!) Overall I found this works and you can use your eye over and over again!