Peruvian Wife Visitor Visa Denied

[acidjiles]

My wife's Visitor Visa was denied for 4.2 with lack of evidence my wife will return to Peru. The issue we have is that while there is no chance she will not be returning to Peru before the end of the Visa there is not a lot of documentary evidence for this. This is because my wife does not have a job as she won't graduate until December and has been a student. Her studies are finished apart from the graduation which should of happened in Jan but due to a university administrative error did not. We provided a letter from her university detailing that she was still a member of the university and that was obviously not sufficient as her visa was denied. I financial support her in the UK and while in Peru her family does. Our long term plan is for her to settle her but she cannot do this without the required English exam which unfortunately in Peru requires full year courses to be able to take whereas in the UK she can just book the exam on it's own so will do that here. Without any additional evidence of ties to Peru I am concerned if we apply again even with a letter from her Father the outcome will not be different. When people do not have official ties to the country like jobs or studies what can we provide to prove she will return which she will without a doubt. Thanks

Edit: My wife was previously here for both a 2 week visitor visa 2 years ago and a 6 month visitor visa until 1 year ago. She studied on her return to Peru. She left on time for both of these but these have been used as evidence she won't return due to having ties to the UK. I am confused how evidence of following rules and demonstrating this is used by the Home Office to demonstrate the opposite.

[acidjiles]

I had originally applied for a 6 month Visa, how much more likely is success if I apply for a shorter period say 2 months if I have no additional evidence to provide?

Also how much would a second failure affect request to join family visa applications?