You can always ask it to continue its sentence. (ref)
For example
Prompt
Some question
Completion/Answer
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore <rest is missing>
Prompt
continue
Completion/Answer
magna aliqua.
EDIT 03/28/2023
For completions that now require continue ChatGPT is sometimes noting
Note: the code above might be split into two parts due to character limits
in the platform, please make sure to combine them before trying to use it.