Retaking IELTS

I’m a native English speaker but needed to take the IELTS for uni admission. I showed up to the exam with 0 prep or any knowledge of the test format and just did it without much thought since I thought it would be a piece of cake. Ended up getting an 8.0 which is a C1 and that feels embarrassing considering English is my best language and I could easily get a C2 or a 9 if I actually tried. Is it worth retaking it and would a 9 on the IELTS help my application to Cambridge Law?