It gets truncated because it's trying to leave enough room for the 'last refreshed at:' text which you see over on the right.
A way around this problem is to not use the group="" attribute at all.
Take that out and instead use a module to do the same thing. GenericHeader is probably the best although you could use StaticContentSample (with CDATA'ed HTML), or ServerSideInclude. Here's a GenericHeader module for you:
<module name="GenericHeader" layoutPanel="panel_row1_col1">
<param name="label">Total sessions done today by all program</param>
That module has no truncation logic so the whole thing will definitely display. And GenericHeader is a reasonable stand-in visually for the group="" header.
Hm. Well then your options are more limited. #1) Only have one panel per row, so the truncation just doesnt kick in #2) have group=" " and ALSO have the GenericHeader module. However in that case the Header and the 'last refreshed' wont be on the same line. If that wasnt acceptable some custom CSS could probably fix that but it'd be a hack and there are significant drawbacks.
3 Apply some custom JS at the app level that just disables the panel title truncation entirely... I could look into that if you were interested (I do consulting around Splunk and Splunk apps; see my profile)