Merging contacts from CRM

I ran a sync from the CRM and it stopped at 2500 which is what our current plan was. I did not realized this happened and then linked that mailing list to my campaign. The campaign went out to the 2500 names. I then restarted the sync after upgrading and another 1200+ names have come into the mailing list. How do I get the campaign sent to the additional 1200+ names? I don't want to duplicate it to the original 2500 but am not sure how to just pick up the new names.

Need to this happen today can you please help me?