So where in our story is the best place to insert an epiphany? The thinking phase of a sequel is a logical place for your character to experience an epiphany, that sudden flash of understanding that provides your character with an opportunity to move ahead. For example,

Your character is devastated that she has just lost several patients to a deadly virus. To no avail, she has racked her brain to think of a successful treatment for the disease. Her mind wanders and she finds herself focusing on some seemingly irrelevant image or recollection. A light within her suddenly goes on when she recognizes a relationship between her problem and the seemingly irrelevant. A solution presents itself.

If the sequel includes either a flashback or a flashforward, a great place for an epiphany is immediately afterward. For example:

In the thinking phase of your sequel, the character vaguely recalls his high-school football coach saying, "What you can visualize, you can do." Your character's mind slips back to that time, and he relives that moment as if it were happening all over again. Your character's mind returns to present, and he goes about his business. A burst of insight (epiphany) shows him that the flashback has helped him see a new course of action.  

If your character has a pesky problem to solve, consider placing a epiphany in the thinking phase of a sequel. Expressed another way, if your story calls for an epiphany at some point, construct a sequel around that decision point and insert the epiphany within the thinking phase.