Answer: He attempts to complete his research before he loses the intellectual capacity to do it.
Step-by-step explanation:
When Charlie realized that he will likely face the same fate as Algernon, he reacted by attempting to complete his research before he loses the intellectual capacity to do it.
He believed that as long as he was able to write, he will continue recording his thoughts in the progress reports. Even though there was possibility that he could have thesame fate as Algernon, he wanted to make sure that his research was completed.