Doncaster have made forward Dany N'Guessan their sixth summer signing.
Tottenham have confirmed that Romanian defender Vlad Chiriches has completed a move to Napoli.
The 27-year-old joined the Seagulls from Spanish club Almeria in January 2013 and has proved to be an important player for them.
Promoted Premier League club Leicester City are reported to be interested in Ulloa, but Hyypia hopes that Brighton can fend off all interest from the Foxes.
“Last season goalscoring was a problem and that is something that needs to be looked at,” The Argus quotes him as saying. “The club has rejected a few offers for him (Ulloa). I need to talk to him. Hopefully he will stay.”
Hyypia has also spoken about his side’s defence for next season.
“With them (right-backs Bruno and Inigo Calderon) we have agreed about extensions I believe,” he said.
“We are trying to get Stephen Ward back (on loan from Wolverhampton Wanderers).”