No, you should not have to; the db engine takes care of that itself.
From Books Online:
"
If the value inserted is larger than the current identity value for the table, SQL Server automatically uses the new inserted value as the current identity value.
"
So, SQL Server auto-adjusts the identity value up as you add higher-valued rows.
SQL DBA,SQL Server MVP(07, 08, 09) A socialist is someone who will give you the shirt off *someone else's* back.