Cedrika Provencher was last seen in the evening of July 31, 2007, near her home in Trois-Rivières. (Canadian Press)

One year after Cédrika Provencher went missing, her family and the police have not given up hope and believe they are "one clue away" from finding the young Trois-Rivières girl.

Cédrika was last seen July 31, 2007, not far from her home in a quiet Trois-Rivières neighbourhood, reportedly telling a woman that she was helping a man look for a lost dog.

Since then, investigators have received more than 15,000 calls, met with more than 600 people and checked some 800 cars in their search for the girl, Quebec provincial police Lt. Francois Doré told CBC News on Thursday morning.

Doré says the case remains "very active."

Martin Provencher in his kitchen on Thursday, the first anniversary of his daughter Cédrika's disappearance. (CBC)

"We're still one clue away from finding her and determining what went on a year ago today," Doré said. Just last week, he said, officers visited a Montreal hotel where Cédrika was reportedly seen.

But there have been no solid leads and Doré acknowledges it's unknown whether the girl is still alive.

Martin Provencher is still optimistic his daughter will be found.

Standing in Cédrika's bedroom, Provencher told CBC News he tries to imagine what his little girl might look like today, but can't.

I have no idea, he says in French, and wonders how grown up she is, whether she looks older.

Martin Provencher has travelled thousands of kilometres across Quebec and New Brunswick in search of his daughter. He said he is still convinced someone besides the kidnapper has information that can lead police to his daughter.

But the ordeal has taken its toll on the family, he says.

The girl's grandfather, Henri Provencher, also helps with the family's efforts to locate Cédrika, who would have turned 11 next month.

He answers the phone in an office in the house that has become the de facto headquarters for the search, jotting down each tip and piece of information people offer him.

"We are in a dramatic situation," he says. "When we are in the water, we swim. It's the same thing for [this]."

Henri Provencher says it's unbearable to constantly think about where Cédrika might be, so he tries to keeps busy but worries about his son.

A special mass is scheduled for Thursday, followed by an outdoor candlelight procession.