If an employee who has been trained, you should be able to participate again in any year prior to retirement, will be to understand the topics and will be update with the changes.
If an employee who has to attend training, it should be repeated every year. Before retirement To understand the topic very well and will be updated with the changes.
If the employees who have attended the training and should join again in the years before retirement, will understand the topics as well, and will update with change.