DD may wish to consider a one-on-one sit-down with her Calculus teacher to review what areas/concepts she is weak in & attack them in the math lab/extra help after school in order to strengthen these areas. It's similar to adjusting her workouts to improve core strength, push-up's, aerobics, etc. No need to go crazy or lose sleep over, but she needs to balance current schoolwork, remedial academics, & PE, along with just having fun by enjoying the rest of her senior year. For example, my DD sets her alarm reminding that it's time to go to sleep as homework routinely is being done til 0130 hours (& others stay up later). Go enjoy HS.
Recommend some Mom/DD alone time, (& Dad/DD alone time too) maybe a weekend trip together; it doesn't have to be fancy or expensive, just go & create some memories of the both of you together to draw on this summer. It meant a lot to my DW. The physical/academic fire hose will be turned on real soon; being able to prioritize & multi-task are skills that will be learned or sharpened very quickly. Your DD will be very glad that she put in the aforementioned extra work before USMA.