I honestly don't really know XD New casts are always awesome, but at the same time I have an attachment problem with characters - I'll miss them immensely if they go XD
Honestly Both ideas can work for you. I'd feel better giving my opintion father down the line but for now I'll say this: I kinda want to see new people.
well I'd say new cast, this way you can work on this current cast and give them lots of good things for them.
I say bring back the season 1 cast for the next season and then go to the 2nd cast. That way the S1 cast can be developed more.
A good writer can take on a challenge like writing in new characters each season. You seem to be doing that pretty well, so I'd say go for the new cast in Season 2.