Back up to cloud from new computer...when files were already backed up on old computer

Using TI2014. I previously had backed up ~250 GB of files onto cloud (and that took a long time), and then had to transfer files from old laptop to new laptop due to various hard drive malfunctions, etc. Once on new laptop, with TI2014 license transferred as well, I went to update the cloud backup with the same ~250 GB of files...and the backup started all over as if no files had ever been sent to the cloud at all. In other words, instead of just checking to determine if any files have changed, and then just backing those up (i.e., differential backup), it's doing a full backup. I don't see any option to just do differential, and thus I am repeating the days and days of backup time required (I only have DSL, so I have to live with that). Am I missing something?

Thanks.