Van den Berg has expressed a strong desire to part ways with Anfield this summer following his successful loan spell at Mainz last season.
Heidel told Sky Deutschland: "We are a bit dependent on Liverpool. I know Van den Berg would very much like to return to Mainz.
"Perhaps the player's voice plays a role in Liverpool's decision.
"It is of course Liverpool's legitimate right to put a price tag on the player. But then there must be a club that is willing to pay that price, and the player must also want to go there.
“At the moment that is not the case, and that is why we still have a chance. If Liverpool loan him another year then we are the perfect club. Sepp would also confirm that. We'll just wait and prepare in case it doesn't work out."