Hello there !!
   Since you are confident that you have made a mistake in the form as well as paid the fees it would not be a good idea to apply again since it may overlap the current application.
    The best thing you can do is to contact the official authorities for the correction of the application.

Glad to be of help, you can check this below link to confirm and get more details.

https://engineering.careers360.com/articles/kcet-application-form-correction

Hey, I don't think it will be a good idea to apply again instead you can go for application form correction. At a particular period of time which will be released official, you will get a chance to correct any kind of mistakes in your form but the correction may be limited to only few fields of the application form. And this correction will only one time opportunity as you won't be allowed to correct again after you have attempted once. So make sure you cross check your corrections. This correction process will be started after the application process is completed. And the time for correction may differ from state to state. For example correction time for Maharashtra starts from fourth week of March 2018 and for Karnataka it starts in the second week of March 2018. So check the correction period as per your location and make sure to make it right in the first attempt. I have provided a link below where you can search for your district CET corrections in the search box. Hope this information is of help.Best of luck.

http://www.sarvgyan.com/articles