Hlp - my bookshelf spkr is like humpty dumpty

Those cheap generic metal stands are killing your sound. Your stands are, almost, as important as your speakers. Thy are a very real/significant extension of your speaker and will effect the sound in many ways. I don't have a clue about your cat. I believe in coupling (as you can read in my review of my monitor speaker stands) so attaching those speakers to your stands with anything less than gravity would be deleterious to your music. Perhaps floorstanders are the way to go. You could always get rid of the cat. Come on, where are your priorities? A cat over your system? good luck. peace, warren

Office Depot sells cheap blue tacky stuff which when placed under the speaker corners and pressed down will certainly keep the speakers in place. Also improves the sound.

Blue Tack or similar product called Fun Tack (made by DAP) available at local Home Depot or Lowe's. Fastens speakers to stands so good that the entire stand and speaker will fall before the speaker comes loose.
Don't use cheap flimsey stands. Get a solid mass loaded stand, well worth the $.

How about concrete blocks for speaker stands. Let's see your cat knock them over! Assuming you don't have a Tiger, Lynx, Bobcat :-)

theres a white tack too samething ,easy to find and cheap less than $2

If you haven't filled the stands do that to give them some heft. Clean cat litter works well. I've seen two or more foot plus long plastic tie downs connected around the speaker and stand. Not the prettiest solution but definately makes the speakers one with the stands.

I'm sorry but there are no fixes for this, I see two choices, First one is get rid of the cat and the second choice would be a new pair of floor standers!:-)
Seriously the blue tack stuff really works.
Happy Listening!