I can get a reference to my customised ribbon and store it in a module
level variable using the following callback:
Public Sub rbxCustomUI_onLoad(ribbon As IRibbonUI)
Set mrbxRibbon = ribbon

However, if my code gets stopped (eg. due to a bug elsewhere) then the
variable holding the pointer to the ribbon goes out of scope. Is
there any other way to set a reference to the ribbon without needing
to close and reopen the workbook?

Thanks a lot,
Andrew