I don't know if someone's said this already but on the guide it says:
Re-Rolling Lifetime Wishes without Choosing Different Traits
If the Lifetime Wish you want for your Sim doesn't appear on the first try, don't fret. Select '...' to change traits, but don't change anything. When you return to the lifetime wish selection screen, the results will change if there are more possibilities. As I said above, if you're really having trouble getting a certain wish to come up, or want to know how lifetime wishes actually work, head to the lifetime wishes guide for the details.
With the generations patch this is kinda outdated because there is the choose custom LTW.
