Login Session

Hi,
We have created an customize theme for wordpress mu/buddpress blog. Now when user login, we display there avatar on sidenav of our blog, http://community.fitnessanywhere.com/.
However if users do not do any activity, there avatar disappear from side nav even if they are logged in. Is there some way, i can change there session to show them logged in even if they login but do not do any activate on blog or browser refresh etc.

Thanks,
Prachi