Yeah…my solution is let the poor girl on the couch A beanbag is nice, but she most likely wants to sit WITH you...not just on the couch
Anyhow, that is only suggestion number one! sounds like she is playing this game because she is wanting you to come and get her. You need to keep her from being ABLE to jump on the couch. The best thing I have found for training dogs to stay off of furniture is to use a house line clipped to her collar and use it to keep her off the furniture... you would step on it when she attempts to jump up. Another thing you can try is putting something on the couch that will either keep her from jumping up (boxes) or something unappealing (upside down plastic carpet runner, with the pokey little spikes up). EVerytime you give her attention to get her off the couch, she is being rewarded. It is best if you can keep her from getting up there with no interaction from you.
Personally, I know VERY few people that require their basenjis stay off the couch...I can't really think of any. Curling up on the couch is one of the great joys of owning Basenjis. It might be a nice compromise to train her that she may come up when you invite her...but get off when you ask. And she may not come up when uninvited. That is definitely possible with any dog...but personally, too much work for me...I let them lounge where they want.
I prefer not to use squirting for most things because the dog is still getting your attention for the naughty behavior. And also they can predict your behaviors that lead up to squirting..so they will think "I will keep doing this until she reaches for the bottle, then I will stop" Also, they will always do the behavior that brings on the squirting when you leave the room, because the threat of punishment is gone.