Well, to raise a boring girlfriend in Saekano, you could start by communicating openly about her feelings. Also, plan surprise dates or outings to spice things up. Another thing is to support her in pursuing her passions.
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Well, you might consider changing her environment or giving her a unique mission. Maybe she gets involved in a mystery or has to save someone. That could spice things up. Also, developing her relationships with other characters in complex ways can make her more interesting.