"Throw back on" is a phrase that can be replaced by several synonyms that will convey the same meaning. One of the synonyms is "revert to," which means to return to a previous state or condition. Another synonym is "retrogress," which implies the regressing back from an advanced stage. "Backslide," "remiss," and "relapse" are also words that can be used interchangeably with "throw back on." These synonyms are useful to employ in different contexts depending on the tone or level of formality that the situation demands. In any case, using synonyms helps to avoid redundancy and adds variety and depth to one's writing and speech.