The Toon have kicked off the season with two defeats.
After their loss at Norwich City, Shelvey said: "Our goal is to stay up. The Premier League gets harder and harder for each season.
"We didn't start well. The boss said during the break that we should increase the intensity. We also did that right after the break, but then they scored their second goal and it punctured us.
"Steve Bruce said afterwards there wasn't much to say. We didn't play up to our level."