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) "It's a dog-eat-dog world, and I'm wearing Milk-Bone underwear." "Norm", on "Cheers". Also from "Cheers", from "Carla": "You need to know 3 things about Tortelli men: Tortelli men draw women like flies; Tortelli men treat women like flies; Tortelli men's brains are in their flies".