Need Advice

Depends on what your system will support. You can try just putting in a clean, new terra cotta pot for them--they'll accept it just as happily, and it won't die. Otherwise, if you tank is mature enough and has enough light, mushrooms, especially hairy ones, are a good substitute. Shrooms are pretty hardy, and aren't bothered by the clowns attention--many other corals don't appreciate the attention of clowns and won't come out with the clowns in there, eventually killing the coral.

Clowns will actually accept just about anything as a host--anenomes really are not needed for their well-being, and as you've found, are not hardy enough for many setups.

There are some lifelike artificial Anemones for aquariums on the market that can be used.