Butler, snared with pick No.20 in the 2003 national draft, has been restricted to just 84 games due to a spate of soft tissue injuries, but remains an important cog in the Eagles' defence.
"The club is poised to launch a serious premiership assault in the near future and it is great to have the opportunity to be a part of that," Butler said.
"As a young player, I was fortunate enough to be a part of the 2006 premiership and that is obviously something I would like to experience again."
Lycett, 19, has played three games for the Eagles but is viewed as a long-term project.
The 203cm ruckman/forward is sidelined by a knee injury.
West Coast sit in fourth spot on the table ahead of Saturday's match against last-placed Gold Coast in Perth.