This would be easier except the values in the status table are expressed as GUIDs in these pre-configured reports, so unless you know where to get those values...
Clone the default report- Count of Assets by Status
Edit this report
Select the pencil icon next to Global Paremeter=Status
change it to parameter type=Basic
type in the value textbox: 492C463B-AFA2-4DD6-AE73-6FD2C7B0E489
leave the prompt user box unchecked
select APPLY
This is the GUID for 'retired'.
Schedule the report to run once a month and that should do it.