The 20-year-old is on loan at the Spanish club from Arsenal until the end of this campaign.
"We are advancing the negotiations to reach an agreement," Mel told Estadio Deportivo.
"This won't be easy but we want to speak in London with clarity and to agree a new loan. I believe that it will be positive for all parties."
Mel has scored two goals in 17 La Liga appearances for Betis so far this season.