The purpose for reimporing the FEM is for HyperSizer to import any changes to the model data, like new grid locations, new elements and new properties (components). If you have not changed the grid locations, there is no need to reimport the FEM so answer "No".
If you have moved/added grids, elements, properties, then you should reimport the FEM and your existing component definition will remain intact within HyperSizer. In other words, you should not loose any of the component setup (sizing dimensions, active failure criteria, etc) for unmodified components during reimport.
**Important - If you've made any changes to the element-component membership in HyperSizer, these will be lost if you reimport the FEM. The element-component membership will be reread from the FEM.
During reimport, new grids, elements and properties are imported and are unassigned in HyperSizer.
Here is a help topic that further describes the implications of Reimporting the FEM.
http://hypersizer.com/help/#FE-General/fem-reimport.php%3FTocPath%3DFeatures%7CFEM%2520Interface%7CAbout%7C_____6I hope this is helpful.
-James