Regarding your question, i found a Q&A section at the vmware certification portal:
Do i have to take the exam within a certain time period after taking the qualifying course?
No. There is no set time frame for taking the exam after attending the class, however, be sure to take the exam before it has been retired.
I think you don't have to re-attend to any class. But this is my personal opinion, not an official one.
thanks for reply