FEMA has just released the 2019 edition of ICS-300 and ICS-400. There is no requirement to retake the courses, but they have made the student material available for review so prior individuals who completed the course can review them.
ICS-300 (SID and last name required)
https://training.fema.gov/coursematerials/downloads?course=ELG0300
ICS-400 (SID and last name required)
https://training.fema.gov/coursematerials/downloads?course=ELG0400
Planning P Videos (Link intentionally broken):
https://www.you tube.com/playlist?list=PL720Kw_OojlJbN2lOfiS43IVO-CMDM9ms