The 34 year old is currently months away from the end of his contract and has previously indicated his interest in staying at the club.
Raul confirmed that while he has received a good offer from the club to extend his contract, the decision will ultimately lie on the shoulders of his family.
"I have got a good offer from Schalke," the Spaniard told reporters on Wednesday evening. "But my family will decide [what I do]."
Addressing his side's meeting with Athletic at San Mames, Raul admitted that Schalke have it all to do after losing 4-2 at home to Marcelo Bielsa's men last week.
"We were superior for 70 minutes at home but tomorrow [Thursday] we must be even better," he acknowledged. "We have to score three goals, so it will be exciting."
Raul scored both of his side's goals in the first leg tie and is set to start again in Spain.