Once you install 1.70 you can get new spellscipts easily in toolset script editor when you open script choosing all sources.
Alternatively if that script would be saved in your module you can get new version in 1.70 builder's resources folder (can be download separately but if you have .exe version its under optional instalation).
I think that if you are updating your old spell scripts onto new spell engine the fastest way is to get know how you changed the spell, then remove it from module, reopen from all sources and repeat your changes into new version.
Tip: I highly advice tool called Beyond Compare. It allows fast and easy files comparing and editing, I work with it daily, its perfect.