Question about evil Morty and the curve

So Evil Morty left the curve by cracking a hole in it and used it to get out but later on the dinosaurs fixed the curve when evil Morty was outside of it and yet he always comes back in it tho if i understand it well it acts as a wall that stops people from outside to get in and people from inside to get out

So how does he come back in it after its fixed and i think he went out after the Rick Prime episode so how does he leave like that when the wall is up?