During the winter, when the plant(s) are dormant is the best. Not during the growing season.

Thanks, I just want to be prepared when the time comes.

Id say early spring before new growth occurs that way they are undisturbed during dormancy, and usually these plants do best when repotted it improves root aeration, and keeps your plants healthy, so check when repotting at late winter early spring.

Here is a link that might be useful: SNW care sheet for sarracenia

I repot mine when I take them out of the fridge in mid february.

Actually, they come out of the pots, get cleaned off and put into zip lock bags in mid fall then into the fridge until mid Feb.

It usually doesn't freeze too much here so I'm thinking of leaving them outside for the winter. Should it start to get really cold I can put them in the attic in front of a window(it can get pretty cold up there too).
It'll be the first year I'm having sarrs and I still have to find out the best way to do it.
I have some sarrs seedlings too but I'm not sure what to do with them this winter(the biggest one just made his first pitcher) I'm trying to find out if I should put them in the attic for their first winter or just keep them warm in front of a window.(I can't get them extra lighting)