In that case it sounds like you need to study harder. Many people would want to be in your situation where simply rewriting IELTS and achieving a higher score will get them ITA. You can chose to do nothing and wait. But then don't complain about waiting since you are making the choice to wait and do nothing rather than taking action and increasing your IELTS score.
why worry if your score will go down!!! you can take IELTS as many times as you can and use the result from one which is the highest score.
it's not like your previous IELTS become invalid once you get the new score. All that matters is the IELTS result you choose should not be older than two years.