The way to do it, in my book, is to export your CVA design to a .CSV file (edit your CVA exercise, use the Design tab, Import/Export Design... button) , then modify that design in the .CSV file to copy the repeated CVA tasks (for test-retest reliability). Then, back in your CVA project settings, increase the number of questions you are requesting to reflect your new design (on the Design tab). Then, import the modified .CSV file (using the Import/Export Design... button).
Just make sure during analysis that you figure out whether to include the repeated CVA tasks in utility estimation, or whether you want to held them out (exclude) them from estimation. You can exclude them or not in your analysis settings.