Scarlett Keeling was 15 when she was raped and killed while on the "trip of a lifetime" in Goa.
Placido Carvalho, 49, and Samson D'Souza, 37 were accused of killing her but acquitted in 2016.
Vikram Varma, who represents the teenager's family, said the India's Central Bureau of Investigation (CBI) had appealed the decision.
He said a hearing was scheduled for Monday and once all the requirements had been met, a notice would be sent to the accused to secure their presence at Bombay High Court.
"I am hopeful for a conviction, but it would be a long walk," Mr Varma said.
The men denied charges of culpable homicide, grievous sexual assault, destroying evidence, assault with criminal force with intent to outrage a woman's modesty and administering drugs with intent to harm.
But they were acquitted by judge Vandana Tendulkar at Goa Children's Court in September.
Scarlett's mother Fiona MacKeown said the legal process was like "a game of cat and mouse".
She said news of the appeal was "great" but that she still wanted a fresh investigation.
"It feels as if things are proactive. But it's nearly nine years ago, I don't know how much longer this is going to go on for."
Scarlett's bruised and partially clothed body was found on Anjuna beach in February 2008.
The police in Goa initially concluded the teenager died accidentally but, after a campaign by her family, a second post-mortem examination in March 2008 revealed she had been drugged and raped before drowning in seawater.
Delays in court saw a trial start in March 2010, but a verdict was not reached until 2016.
An appeal has been lodged in the case of a Devon teenager killed in India in 2008, her family's lawyer has said.