The family announced plans Wednesday morning for a new search that will take place on Sunday at 9 a.m.
"We will be combing new areas," said a family spokesperson. "We will be going door-to-door passing out fliers."
"We will never give up on you, Dulce Maria. And we are asking you, the public, not to give up on her."
The five-year-old was reported missing during a family outing to Bridgeton City Park on September 16.
Timeline: Disappearance and Search for missing 5-year-old girl Dulce Maria Alavez
The girl and her 3-year-old brother were playing while their mother sat in her car with an 8-year-old relative, but her son soon ran to the car crying and pointed to the area where he last saw his sister
There is a $52,000 dollar reward being offered in the case.
Eight-year-old Camila Alavez is Dulce's aunt, but family member say they were more like sisters.
"I miss her a lot and I want her to come back," Camila said.
She and Dulce's brother, Manuel, held up signs of support as family members and friends spoke on Wednesday.
Police recently released a sketch of a man they describe as a possible witness.
During the news conference on Wednesday, the family spokesperson also thanked local law enforcement for their efforts but said the family has not heard from investigators in a few weeks.
"They're not blaming the police, they're just upset there are no answers for them," she said.
The event on Sunday is an all-volunteer search effort. All volunteers are asked to meet at Bridgeton City Park at 9 a.m.