@gittek,
You can scale-up or scale-down the chart before exporting using exportChart method and reset it back soon after exporting. Please take a look at this JSFiddle for a working example.
If the solution suggested doesn’t fulfill your requirement, kindly create a sample project reproducing the issue you are facing and share it with us over Google-Drive or Onedrive so that we can look into the code, understand the scenario better and help you out.
—
Thangaraj Raman
Team CanvasJS