When you're sitting down and she is thinking of crawling up on your lap....at the very first intention, BEFORE she does, give her an alternative.... show her where you DO want her to lie down. Make it as close to what she would like as possible, like a blanket on the floor near you, if you don't allow he to be on the furniture. You'll need to find a reinforcer for this. What is it she wants so badly that she wants to climb onto your lap? That which she is seeking IS the reinforcer in this instance. Give her plenty of stroking and attention when she lies on her blanket or dog bed. Once she starts getting the hang of going on this blanket, start adding a cue word to go with it while she's lying down. You can even give her her favorite toy or treat. She may get up again and try again and you just have to repeat what you did, jumping up many times from the couch for a while until she finds out that it doesn't work to try and crawl up on your lap. Stick with it religiously. One time where she succeeds, where it works for her.....she'll keep trying that then.
Ignoring works for attention seeking behaviors, like jumping up when you're standing up because you can remove yourself easier and make it impossible for her to get what she wants by jumping up. If you're sitting on the couch and she climbs into your lap, ignoring her won't work because she's still getting a payoff.....being close to you and sitting on your comfy lap. So, in that case, just ignoring won't leave her empty "handed." She still gets something nice. So, you can give her an alternative behavior which will give her a payoff, hopefully, as close to resembling what she'd like as possible.
For people who don't want their dog on the furniture, a cushy dog bed which can be placed near the furniture can be something the dog can be re-directed to and praised/treated for using that. It just takes time, consistancy, and patience...showing the dog what she is allowed to do and reinforcing well when she does it.