Symptoms
Will SharePoint re-attempt event-receiver-triggered K2 Workflows that have failed to launch?
Diagnoses
There is not built in functionality to automatically re-attempt failed workflows in this context.
Resolution
As an alternate check for workflows that haven't fired for a given item, you could have the workflow set a column or SmartObject boolean value to true if a workflow has been launched for said item. You could also create a workflow that loops through each item, checking this boolean field, and for all false values, that launches sub-workflows for all items that didn't have a workflow trigger. This could be scheduled to run regularly, or be an on demand process as well.