Sylvan and company: Thank you! I will try the downsizing and careful watering. I got my Peace Lily as a wedding present 21 years ago--I really, really don't want this baby to die. It is at work now as my kittens bit the poor thing to shreds. So, seeing as it had some black leaves (as well as fang marks) I researched about black leaves and changed the soil and, oops, enlarged the pot. Now it is putting out lovely little green leaves--which are turning black and brittle. Another peace lily at work got frozen during a power outage last year. Its leaves turned black and many fell off/were pruned, but it looks great now. We are kind people, who hate to see something killed--that's why we struggle with these plants. A 6-foot tall dracaena at work was locked in an unused office for a month or so and nearly died, but I've been watering it and it is sprouting new growth. I feel great! :-)

thats what I suspected. It does dry out- seemingly more than 'normal'. Any suggestions on remedies? I repotted it with a nice mix of potting soil and humus. thanks!

It looks like something caustic got spritzed on the leaves, or drops of plain or fertilized water while sunlight was shining directly on the leaves. The pic is kind of blurry, it could be some kind of bug/larvae that eats the top or bottom surface of the leaf, but the pattern doesn't look as likely for that, IMVHO.

It looks fine/good. I’d leave it alone, let it settle into your home and the window/light you’re offering, and water when it needs it instead of “once a week.” If you broke up all the roots when repotting (which would be ideal), then it needs time to reestablish itself, and even once a week may be more/less than what it needs. I’d let it settle for a month or two, too, before fertilizing it.