Here are the steps to be followed:
1) Enter your data which contains the columns and rows of information
2) Then select this data and on the home tab in Excel application click on Format as Table button and select any desired format
The above said step applies Table format to your data. Once the table format is applied to the data, navigate to Data Tab and click on Filter button to remove the filter
3) Now, create the graph using this data i.e. select your data and go to insert tab and click on the desired chart. This will create the graph on your current worksheet
4) Once the chart is created, right click on the chart and click on Select Data option and modify the data series
With all the above steps, you have completed the graph creation and now, if you add a new row to your table, the table format gets automatically gets extended and the graph gets updated accordingly.
The Table format is available on Microsoft Excel 2007 onward. I hope you are using a latest version of Microsoft Excel, where the above said operations can be performed with out any issues.