Extend Value to all Weeks going forward

Hi TD 

A Power Query option is attached

// ExpandWeeklyValue - can be shortened
(table as table) as table =>
let
    Source = table,
    MinDate = Table.Min( Source, {"Week Ending"} )[Week Ending],
    MaxDate = Table.Max( Source, {"Week Ending"} )[Week Ending],
    Weeks = ( Duration.Days( MaxDate - MinDate ) / 7 ) +1,
    DateTable = Table.FromColumns(
        { List.Dates( MinDate, Weeks, #duration(7,0,0,0) ) },
        type table [Week Ending = Date.Type]
    ),
    MergedQueries = Table.NestedJoin(
        DateTable, {"Week Ending"},
        Source,    {"Week Ending"},
        "Source", JoinKind.LeftOuter
    ),
    Expanded = Table.ExpandTableColumn( MergedQueries, "Source",
        {"Item", "Available Value"}
    )
in
    Table.FillDown( Expanded, {"Item", "Available Value"} )

// Query
let
    Source = SourceTable,
    GroupedItem = Table.Group( Source, {"Item"},
        {"ItemTable", each _,
            type table [Week Ending=nullable date, Item=nullable number, Available Value=nullable number]
        }
    ),
    RemovedItem = Table.RemoveColumns( GroupedItem, {"Item"} ),
    AddedExpand = Table.AddColumn( RemovedItem, "ExpandedItem", each
        ExpandWeeklyValue( [ItemTable] ),
        type table
    ),
    CombinedExpandedItem = Table.Combine( AddedExpand[ExpandedItem] )
in
    CombinedExpandedItem

I have 960 different Items
If you don't have external connections I would suggest you disable Background Data and Ignore the Privacy Levels under CURRENT WORKBOOK in the Query options (if not clear let me know)

(Glad to re-create existing data)