+100 CR in a month for International student.Possible??

Hello everyone,I will take the SAT this October and my CR is terrible.I have done a SAT practise test recently and scored 800 in Math and 650 in Writing (,but my CR remains below 500.Can someone give me an advice, i have only a month left before i take the next SAT test.I really want to score more than 2000 in this test so i can be better in January.