Whensoever is a somewhat archaic word that means at any time when. It can be replaced by a variety of synonyms to add variety and interest to your writing. Some good choices include at any time, whenever, at any point, at any moment, or anytime that. Another good option is the phrase whenever it occurs, which can be used to describe an event or situation that could happen at any moment. No matter which synonym you choose, be sure to use it in a way that makes sense in the context of your writing, and be consistent in your usage throughout the document.