Modal Dialog size

We display a modal dialog when a link is clicked on a portlet. The very first time the link is clicked, the dialog is shown and the size of the dialog is same as the size in the dialog’s display property tab (using the designer). However when the link is clicked again, the dialog is displayed but the size of the dialog changes and the dialog’s UI is cluttered.

Is there a way to control the size of the modal dialog? May be through javascript?