The first semester is done and dusted and a new blank canvas is in front of each student. Learning from mistakes is a powerful tool if the energy is harnessed correctly.
What is one thing I could have done differently to improve my grade?
Am I willing to take advantage of the resources available to me?
If I turn in 100% of my work, what kind of margin does that give me if I am not a good test taker?
What second-semester grade and grade on the final will boost my first-semester grade up a letter?
If I take and score well on the AP test, can that offset the lackluster grade on my transcript?
Surprising to some students is the fact that many schools will not use your first-semester senior year grades in their application review, so the transcript gig is up after Junior year. For example, the University of Maryland College Park does not review mid-year grades and early action applications account for about 97% of admitted students. The University of South Carolina does not review first-semester senior year grades if you are deferred to regular decision. On the other hand, Clemson and Auburn do! University of California schools do not review mid-year grades. See state flagship universities' mid-year report requirements.
One caveat, just because senior grades might not be reviewed, doesn't mean that admissions aren't closely monitoring the rigor of the classes you chose to take as a senior. Take a full course load senior year.