Brentford offered the midfielder the chance to return to football in January following recovering from a serious heart ailment.
The 30-year-old signed a contract until the end of last season and made an impact in the Premier League, which has led to interest from several clubs in Europe.
Several Premier League clubs have held talks with his agent and Manchester United have also offered him a deal to join them in the summer.
Brentford want him to sign a fresh contract to stay, but Frank conceded that he still does not know what the Dane wants.
He stressed that Brentford are still in the running and claimed that the player will contact him once a decision is made.
Asked if Eriksen will continue at Brentford, Frank told Spanish sports daily AS: “I don’t know, honestly.
“I know we still have a chance and I hope he will make the decision in the next two weeks because he is on holiday now.
“The agreement is that he will call me and tell me what he wants to do.
“He hasn’t decided yet.”
Tottenham Hotspur have held talks about signing Eriksen, but the trail has gone cold in recent weeks.