Return ticket is no problem. She'll have that. Re new job starting, wouldn't they want to see evidence of this? I don't think it'll be possible (if she did find a job before her trip, her employer would not allow her 6 weeks before she has to start).
We are planning another visa application (probably a spouse visa) and I'm happy to tell them that - I just think this is a great opportunity for her to spend more time in the UK. It's clearly not a holiday - it's about acclimatising to UK culture, and I think this is a better way of doing it rather than multiple 2 week trips.
But I could be totally wrong about that and maybe this is not the way to go. I want to hear from anyone who has done something similar.