Deleting and Inserting set of records based on Date Field

Hi Experts,

I am trying to update a table with last two weeks data on daily basis.

I first delete the last two weeks data based on a Date Field in the Table. For this I get the system datetime and do something like: 

Where Clause - > DateField = Getdate()-11 days.

While inserting, I do the same. However, the time lapse in the system date between the delete and insert is causing the data to lose.

I am quite new to these tasks. I appreciate if anyone could help me a step by step approach on how to do achieve my requirement.

Or any links to guide me will help.

Thanks heaps in advance.