String pattern replace a column
SELECT REPLACE(
           REPLACE(YourColumn, '$[%]foo##amet[%]$', 'amet'), '$[%]bar##[%]$', '')

SELECT REPLACE(REPLACE(YourColumn, ' $%amet%$ ', ' amet '), ' $%bar%$ ', ' ')

CREATE FUNCTION [dbo].[ReplaceWithDefault]
(
   @InputString VARCHAR(4000)
)
RETURNS VARCHAR(4000)
AS
BEGIN
    DECLARE @Pattern VARCHAR(100) SET @Pattern = '$[%]_%##%[%]$'
    -- working copy of the string
    DECLARE @Result VARCHAR(4000) SET @Result = @InputString
    -- current match of the pattern
    DECLARE @CurMatch VARCHAR(500) SET @curMatch = ''
    -- string to replace the current match
    DECLARE @Replace VARCHAR(500) SET @Replace = ''
    -- start + end of the current match
    DECLARE @Start INT
    DECLARE @End INT
    -- length of current match
    DECLARE @CurLen INT
    -- Length of the total string -- 8001 if @InputString is NULL
    DECLARE @Len INT SET @Len = COALESCE(LEN(@InputString), 8001)

    WHILE (PATINDEX('%' + @Pattern + '%', @Result) != 0)
    BEGIN
        SET @Replace = ''

        SET @Start = PATINDEX('%' + @Pattern + '%', @Result)
        SET @CurMatch = SUBSTRING(@Result, @Start, @Len)

        SET @End = PATINDEX('%[%]$%', @CurMatch) + 2
        SET @CurMatch = SUBSTRING(@CurMatch, 0, @End)

        SET @CurLen = LEN(@CurMatch)

        SET @Replace = REPLACE(RIGHT(@CurMatch, @CurLen - (PATINDEX('%##%', @CurMatch)+1)), '%$', '')

        SET @Result = REPLACE(@Result, @CurMatch, @Replace)
    END
    RETURN(@Result)
END