How is character revealed in Lady Macbeth in which she shows respect towards human life? How does she react to human life (when someone has died)?

First, while Macbeth is offstage murdering Duncan, Lady Macbeth speaks to herself alone on stage, saying, "Had he not resembled / My father as he slept, I had done 't" (2.2.16-17).  Lady Macbeth had prayed to become ruthless and remorseless, and yet, she still seems to retain some compunction: she could not murder Duncan herself because he looked too much like her father.  In this way, then, she seems to retain some sympathy in her person, some respect for human life, because she finds that she is unable to take it when the chips are down.

Later, in her sleepwalking scene, we see Lady Macbeth's guilt for the lives she and her husband have taken on full display because she is asleep and cannot control her behavior or speech.  She seems to relive, in part, the night of Duncan's murder, crying, "who would have thought the old man / to have had so much blood in him?" (5.1.41-42).  She believes that his blood still lingers on her hand, a symbol of her terribly guilty conscience; obviously the blood is gone but the guilt and regret remains.  Further, she asks, "The Thane of Fife had a wife.  Where is / she now?" (5.1.44-45).  She knows, then, that her husband has murdered Lady Macduff and her innocent children, and Lady Macbeth regrets her husband's brutality because she now seems to have more respect for human life than he does.  At first he was somewhat more scrupulous than she, but now it is Lady Macbeth who appears to have greater respect for life while Macbeth only seems to respect power.