How to daily append data on a Dataset connected to a Data package

[hakkthan]

Hello guys,
I very happy to meet you all. This is my first post here. In general, I am a newbie in Cognos analytics platform. The last 6 months the company I work for decided to move to cognos analytics 11.0 platform in order to built a BI environment for all of us business users. Since now, we were working on Ms Power BI. So I have many questions to ask, but I am gonna start with the most important one. So, enough with the intro lets move to the point.
I have built a query that is comparing a specific set of data for a specific date with a set of data for the next 30 days with a simple join. So daily this query is running a specific time and sends me the results. Then I have a excel file that I copy paste daily data in in order to have a full set of data (for all the days that the query had run since the day I built it. Then, I upload these (actually there are two excel files) full datasets into cognos, make a data module to combine some extra mappings and based on that I make a Dashboard. And here is the question how can I a make the initial query to append the daily results into cognos, in a dataset every day that runs.
I know how to make a dataset connected to my data package but doing so every day that the dataset will be refreshed the yesterdays data will be deleted and the new ones will be set on.
I want both (all) of them to be available in my dataset, so I need a way to say to my query instead of delete and refresh the dataset, to only append the new data in.

I hope you understand my question.

Thank a lot for your time....