Do clothes become impure by touching a blanket their owner slept on, given that the blanket was previously touched by an impure liquid, was not purified, and there was no trace of that liquid?

A thing that has become impure due to a liquid impurity does not transfer that impurity to dry objects it touches if the impure thing itself is dry, even if a dry trace of the liquid remains on it. Therefore, covering yourself with it and sleeping in it after some time will not render your clothes or body impure if they are dry.