In most cases, you don't want to make the election to restart depreciation.  In most cases you'll want to continue to depreciate the carryover Basis from the previous property (using the old placed in service date), then add a second asset to depreciate the 'extra' amount paid (using the new placed in service date).

You don't NEED to use the Cost Seg, but it can often be beneficial and your client paid for it, so why would you not want to use it?