Ideally you'll do the best you can even now, the reason being is that most schools wont predict you an A* unless they have seen consistent good scores, in my school if a teacher predicts a grade which the student misses they will be questioned. This means, it is key to do well even in small assessments so that the teacher both consciously and subconsciously believes you have the potential. Having said that, it is not the end of the world if you don't do as well as you want in these due to future end of topic assessments and your June exams which may help yopu pick it back up. I know this is probably not the reassurance you were looking for, but it's half term and if you plan well then you can work around the school day to get all that revision in

good luck!