The Terriers are languishing at the bottom of the table, 16 points adrift of safety, and having won just three times this campaign.
Siewert said: "If you think of how many games we have won since March last year - it is four.
"This is important to know, and it says something, we have to look at everything.
"It's about having a long-term view of how we can change it - the thing is a work in progress, and we are in good contact (with owner Dean Hoyle).
"We have a long-term idea and there will potentially be a lot of changes.
"I knew it would be a difficult situation, I'm not here as a magician, but I'll give all my energy for the long-term to find the solutions the club need."