Your cats now think of your blinds as a play toy, so you need for them to forget about them and move on to something else. Do they have other toys to play with while you are gone? Could you get some window tinting to put on your windows so people can't look into your apartment, then put the blinds all the way up so the cats can't play with them.

I totally understand your problem! Our last apartment we had to pay three hundred dollars when we moved out to replace the blinds our cat had jumped through bending the corners until they broke off.
My husband always wanted to keep the blinds up to avoid this problem,but I'am like you and dont want people looking in my windows.
You could try getting some long curtains that cover the whole window and make it harder for your cats to get in the window.
Or,it is winter now and putting that plastic over your windows will help seal in the heat and keep the cats out! Only draw back is no opening the windows until spring!

There are things to spray on stuff to make is unappetizing for chewing. Bitter apple, etc. Look in Petsmart.

Also, you can try the sneaky spray method. Lay in wait with a well aimed spray bottle and squirt them when they do it. But don't yell "No!" or make them think you have anything to do with the squirt. They have to think it's the blinds' effect.

Do they just want to sit in the windows and see the world? Could you leave the blinds up 10" or so so that they can do that?

My cat took a liking to jumping up on the low TV table...not a good place for her with all of the wiring in back of the TV). I put rows of double stick tape on a piece of cardboard and anchored the 'sticky' cardboard to the table with masking tape. She tried jumping up once or twice, but hopped right back down. She hasn't shown interest since.

I got the idea from reading about a product called Sticky Paws made expressly for that purpose. Its a double stick tape that is not supposed to leave a residue on the surface you are sticking it on (but I would test it on the blinds, first just to make sure).

It sounds like they just want to get up on the windowsill so they can look outside. Cats won't usually jump onto a surface unless they have space to land, so fill the windowsill area with something (cardboard boxes, bags of sugar, books, whatever). Or put something over the window so they can't see out, like that "stained glass" or frosted adhesive-backed plastic. Then they'll have no reason to jump up there.

You could also try taping sheets of flimsy cardboard to the windowsills, so that several inches of cardboard hangs over into the room. They will jump onto the cardboard, it will bend, and they will fall to the floor (unharmed). After a few tries they'll give up.

My cats love looking out the windows. My oriental pulls the blind away from the window and crawls behind. I have the 2" wood blinds. He has done this for 6 years and has caused no damage.

I'm with cynthia. just raise the blind a little. You could probably lower it at night. My cats only crawl behind the blinds during the day so that they can look out and sun themselves.

Raising the blinds a little isnt going to help if they are chewing on them like vaccumfreak said they were.
Most apartments DO charge too if they are damaged at all.300 dollars is alot of money for some stupid blinds.

My apartment is bottom floor too,and they are more prone to break ins.It makes more sense to want to keep the blinds closed.
My cat is VERY spoiled,but after shelling out 300 bucks,it is one luxery he will have to live without.

You could also take your blinds down and put them away,and install some cheap twenty dollar blinds from somewhere like WALMART (the plastic kind)
That way if they get messed up you wont have to pay for them.I plan on doing that in the spring but right now I have plastic over my windows and I dont have the money to buy several sets of cheap blinds (I have alot of windows) with Christmas coming up.