Pitcher plants in nature catch whatever comes their way. There are no plugs. They could have a boatload of bugs in their pitchers and that's okay. If a leaf / pitcher turns brown.... so be it. Cut it off and toss it. There's more pitchers to handle the load.

Some people plug a few for looks sake using cotton balls.

Plugging them seems just wrong, somehow.

Petiolaris is correct. Just let them go their merry way. When individual leaves brown and die, you can remove them and sweeten up your compost pile.

Don't worry ,I had never the intention to plug my plants, I was just curious about how it would work.
I let my sarr munch away and I think a nest of ants has discovered them(the little brown ones not those big ones). After many days of rain the sun came out and the ants are now running around my sarracenia plants so I'm assuming they'll get their share (they'll have to fight the little spiders that made their home between my plants for the ants).