Insert cell in Excel w/o changing the range of a formula

I have an excel worksheet that is recieving a dynamic stream of data. Once every second, a value enters the cell D1. I have written a simple VB script so that once the value arrives, the cell is shifted down. I have several chart linked to the data, and the problem is that once the data is shifted down, the range of cells being plotted to the chart also shifts. I need it to stay fixed. My VB code can fix this, but it seems to take a lot of computing time and I was hoping there was a way to prevent Excel from automatically changing the range of cells a chart reads.