DBCC CHECKIDENT Checks the current identity value for the specified table and, if it is needed, changes the identity value. You can also use DBCC CHECKIDENT to manually set a new current identity value for the identity column.
For example, YourTable has 45 rows with 45 as last identity.
If we want next record to have identity as 55 we need to run following T SQL script.
DBCC CHECKIDENT (yourtable, reseed, 54)