The club are languishing at the bottom of the table and are 16 points from safety, having won just three times this campaign.
Speaking ahead of this weekend's Premier League clash away at West Ham United, 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."