If you're using
SQL Server 2005 or above, you can do it like this (I'm using CTE to generate dates between min and max dates):
DECLARE @MinDate DATE, @MaxDate DATE;
SET @MinDate = (SELECT MIN([Date]) FROM [TableName]);
SET @MaxDate = (SELECT MAX([Date]) FROM [TableName]);
;WITH Dates
AS (SELECT [Date] = @MinDate
UNION ALL
SELECT [Date] = DATEADD(DAY, 1, [Date])
FROM Dates
WHERE [Date] < @MaxDate)
SELECT ISNULL(t.[Party Name], '-') AS [Party Name],
d.[Date]
FROM Dates AS d
LEFT OUTER JOIN [TableName] AS t
ON t.[Date] = d.[Date]
ORDER BY d.[Date]
OPTION (MAXRECURSION 32767);