You can modify the Turabian 8th Footnote Style to use the Short Title field. In EndNote, click on the Edit menu > Output Styles > Open Style Manager. Browse to the Turabian 8th Footnote Style and double-click to open it. On the left side of the Style, look for Footnotes. Under that, click Templates. Here you will see the standard templates as well as the Sort Form for each reference type. Repeated references in subsequent citations will follow the Short Form. You can modify these templates to use either the Title or Short Title. Place your cursor in the appropriate template position and use the Insert Field button in the upper right corner to add Short Title. Keep in mind also the setting at the top: “When using the short form, include the title field only when needed to disambiguate a citation.” You can uncheck this if you always want the title to be included.
When you are done editing, click on the File menu and select Save As. Select a name and then Save the new copy. You can then close the Style and Style Manager. To see the changes in your document, be sure to switch to the new copy of the Turabian 8th Footnote Style.