The Switzerland midfielder has been linked with Liverpool since the end of the season.
"I'm not going to go through another year like this," he said. "If not much changes, then I will have to change something."
Liverpool and a host of clubs in Italy are reportedly tracking the midfielder, who scored six goals in the Bundesliga last term, although he has a contract with Bayern until 2016.
"We'll just have to see what happens," he added. "I'd only be interested in a club who could challenge for silverware."
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