Skyrim: Wasted all J'zargo's scrolls

I have wasted all of the J'zargo Experiment scrolls on enemies not the undead. And I am too far in the game to reload. What to do now?

These scrolls are part of the quest J'zargo's Experiment. Sadly, there's no (in-game) way to get more if you've used them all up on the wrong enemies:

If you use up all ten scrolls without killing three undead enemies, the quest will be failed.

The only reward for this is J'zargo will be willing to be a follower for you - there's no questline this locks you out of, etc - so you might just give up and move on.

Another alternative is to use the console, if you're on the PC. Try:

resetquest MGRAppJzargo01

which should reset this quest and allow you to retry it.

If you haven't talked to J'zargo and failed the quest, you might also be able to just give yourself more scrolls:

additem 000967e3 10

should give you 10 more of the relevant scroll.