You can most certainly improve your grades from AS to A2. I got AABC at AS and got AAAB at A2 and I got the As only one of my A grade subjects at AS and the others in the one I got a B and a C in. I resat my AS lit exam and went from an E to an A so if you put the work in it can pay off. Resit some of the modules you got lower marks in and you can get those higher grades.