What are Dr. Manette's "reiterated instructions" to Charles in preparation for the trial?A Tale of Two Cities by Charles Dickens

When Charles Darnay arrives in France, he is amazed at the
changes that have taken place since his departure.  As he travels toward Paris, the
atmosphere heats up and many angry revolutionaries call out to him, "You are a cursed
emigrant."  Charles learns that two new decrees affect the French emigrants:  There
property can be seized and they can be banished, and if they return, they can be
executed.  As he nears Paris, Darnay is given escort and, shortly, arrested and taken
prisoner.

After Dr. Manette, who is recognized by the
revolutionary court as “a notable sufferer under the overthrown system” is allowed to
enter a plea before “the lawless court” to free Charles Darnay, the court refuses but
Dr. Manette is allowed to remain nearthe prison to assure that Darnay is safe. Using his
influence as the Bastille prisoner, Dr. Manette becomes the inspecting physician in La
Force. In this way, he is able to see Darnay on a regular basis, an arrangement that
comforts Lucie.

As the trial day approaches, Manette
instructs Darnay how to conduct himself during his questioning.  Because of the new
decrees about emigrants, it is of paramount importance that Darnay stress the fact that
he is not an emigrant; instead, he must clarify the point that he has voluntarily
relinquished his title because it hs been "distasteful" to him and explain that he
receives no revenue from the Evremonde estate, but, instead, "lives by his own industry"
in England.

To further emphasize that he truly loves
France, Darnay is instructed by Dr. Manette to mention that he has married Lucie
Manette, who is, of course, French.  In addition, Darnay is to mention that his motives
for returning to France have been to save a citizen's life by bearing witness to the
truth of his testimony.

At his trial, Dr. Manette and
Theophile Gabelle are witnesses to the proof of his declarations.  After Dr. Manette
testifies on Darnay's behalf and calls upon Jarvis Lorry to corroborate his testimony,
the voices cry in favor of the prisoner, and Darnay is declared
free.