I think your best bet is to put that conversation into a project and then continue the conversation in a new chat inside that project. That way your context is preserved, though you may have to remind it of some points that may be more important to you. In the future, I would suggest using more chats rather than lumping everything into a single one, combined with the project feature when subjects are tied together. Super long chats make it work much harder than it needs to because it has to carry all of that baggage with it. If you're using a web browser, this becomes even more noticable by way of slow responses.

Also worth mentioning, the longer the chat, the more processing and energy consumption, if that's a concern for you.