ESOPs were not always part of and eligible for the pre-approved/volume submitter document program. I think it was just the prior cycle for which that was available. That means the plan was individually designed by definition - regardless of the document platform that was used (like cash balance plans years back).
Like cash balance plans, or any plan for that matter, the ESOP was not required to be put on a pre-approved document. You can always remain individually designed, in which case you need not and can not submit an updated document for a determination letter, except for an initial determination, plan termination or other special circumstances defined by the Secretary. However, individually designed plans are still required to be amended timely for changes in the law and periodically restated after a certain number of amendments - you need not restate every 6 years as with pre-approved documents.
Look at the existing document, it's determination letter and the prior 5-year cycle under which this came. It might be a cycle B or C plan for which a 2013 restatement would be appropriate - BUT, they should also then have any and all required interim amendments for ESOPs, adopted timely (which is, as you know, one of the primary advantages of using a pre-approved document).
So even if the intent was adopt a new pre-approved document as evidenced by a resolution, the lack thereof may not be a compliance issue. Updated SPDs are also a periodic requirement and may not necessarily mean a restatement was prepared.
Hope this was helpful and good luck.