Sorry, I should have been clearer in my original question: Does the Desktop Reader prompt you to save your form on exit? That is, are you training your Desktop Reader users to select the "Don't Save" option on exit? Or alternatively, does the form have some sort of script that resets the form content prior to save? If you suspect the latter, it may help to send me the form in question (adobereader-ios@adobe.com) and reference this forum thread.
Something that would work with the iOS Mobile Reader would be to embed a script that resets the form content on Document Open. This way there is no training required; the form is reset automatically during open before the user sees or interacts with the form. Where this could be a problem is if the prior data is sensitive -- even though the content is being reset on open, the old content was included in the last save and if somebody was capable, they would be able to get at it. A script that resets the form content immediately prior to save would solve this issue and be preferable, however, the current version of the Mobile Reader for iOS does not have support for executing script immediately prior to save.