I feel like the welcome to Derry ending for season 1 is enough. It should end there. If you start to go into time travel. It creates a complicated paradox. The creature will ultimately die and the outcome will not change. It was a great series but I think where it ended is perfect. It will start to get redundant if It keeps going back to the past to try to change the future. Just my opinion. The book by the way is so good. Im rereading it again.