Hello,
2008.2 (the current release), is backwards compatible with 2008.1 and contains additional bug-fixes and small features added to all controls, plus 2 brand new controls - WebHierarchicalDataSource and Slider. So I believe you can safely re-download it and evalute again, things are pretty much the same.
In any case, if you do need 2008.1, I guess you can contact our Developer Support department and ask if a download link is available for re-downloading. DS can be reached at:
http://www.infragistics.com/gethelp/default.aspx