Long ChatGPT chats go bad but starting a new one means losing all your context. How do you actually deal with this?

Every time I get deep into a long conversation research, writing, problem solving, coding I hit the same wall. The chat gets long. Quality starts dropping. ChatGPT starts missing context from things I said 40+ messages ago. Responses feel less sharp. So I opened a new chat. Instantly feels better. But now I've lost everything the background I spent 20 minutes giving it, the decisions we worked through, the specific framing that was finally working. I've tried the "ask it to summarise everything and paste into a new chat" approach. Works sometimes. Fails other times.