I transited through MIA again last week and took approx 1 hour from getting of first flight to being at gate for connection. Immigration moved quite quickly and baggage delivery was fast, although this is not always the case at MIA. 2 hours should be plenty but there are AA staff in the immigration hall so if she is tight on time speak to them, i have seen them move people up in the immigration line. She will have to collect bags and then drop it with AA again after customs and then go through security. The "skytrain" that moves you between gates is quick and efficient and saves a long walk.