I need to replicate between tables with different structure SQL 2008

I have a single table with the same number of columns with all the same column names that I need to replicated. I have a column that is a INT data type that needs to be changed to a BIGINT data type.  The column is a identity column that is reaching upper limits and part of the PK.  The table has 250 million records and very little downtime.  I was thinking of replicating the table to reduce the needed downtime to change the data type.

Help.