You can make a copy of an existing form to use it for a new purpose. Copy the form you had saved earlier by opening it through the modification link in your email. Select Actions - Make a copy.
Continue to modify the form as if it were a new form. The changes you make to the copy will not affect the original form in any way. Make sure that the settings are suitable in all stages of the form for its new purpose. Note that a logo, for example, will not be transferred to a copied form.