Date Filter not change when new data added

Hi NewbieJono ,

Do you want to set the default selection of Date slicer with latest date? If yes, you can refer the following links to achieve it.

latest date in the slicer

Slicer Date column = IF ( 'date table'[Date] = MAX ( 'date table'[Date] ), "Latest Date", 'date table'[Date] & "" )

Select latest date in Slicer

Default Slicer Value = 

VAR MaxDate = 
CALCULATE(
    MAX( Dates[Date] ),
    ALL(Dates[Date] )
)

VAR Selected =
SELECTEDVALUE(
    Dates[Date],
    MaxDate
)

RETURN
Selected 

Best Regards