Note:
Normally when a user calls a stored procedure, SQL Server does not create a new data access plan to retrieve the information from the database. The queries used by stored procedures are optimized only when they are compiled. As you make changes to the table structure or introduce new indexes which may optimize the data retrieval you should recompile your stored procedures as already compiled stored procedures may lose efficiency. By recompiling stored procedures you can optimize the queries. There are different ways in which you can force SQL Server to recompile your stored procedure.
exec sp_recompile MyTable
CREATE PROCEDURE usp_MyProcedure WITH RECOMPILE
EXEC usp_MyProcedure WITH RECOMPILE
MYQuery OPTION (RECOMPILE)