Just to clarify, if the IR has expired by more than 7 years you will need to do just the IR exams again (not all of the ATPL exams) and complete mandatory refresher training, which, according to the Regulation, means doing the initial IR course again.
To get an EASA ATPL, you must also have a minimum of 500 hours multi-pilot time and (I believe) a valid MPA type rating. There are still a significant number of people holding CAA national ATPLs who do not meet this requirement and will only be able to convert to an EASA CPL. For them, it will be necessary to pass all of the EASA ATPL theoretical knowledge examinations in order to get an ATPL back again.