This is very much an individual decision based on many factors. It depends on the individual student and their circumstances.
You should consider whether you need to improve your grades for your first choice university course or whether you should revise your ambitions according to your achievements to date.
You will need to be clear in your own mind as to why you did not achieve the grade you hoped for previously.
There are many contributing factors. You may feel that your predicted grades in 2020 were incorrect or unfair or perhaps you simply did not work hard enough during the year.
In order to successfully resit A levels, being taught in focussed, small classes by specialist staff who are highly experienced in this area will increase your chances but you will also need a clear motivation for study and be prepared to put in a lot of hard work.
Since 1984, many students at RIC have successfully retaken their A levels and gone onto their first choice universities.