I made a sim that like to build a family but I've notice that having a wife and kid gave me a hard time building up my career and make money. Can we change his aspiration so he would focus on other daily wants like making money ? Or I have to make a brand new sim ?
I believe there is an item purchasable with aspiration called the ReNuYuSenso Orb that can change your aspirations, turn-ons, and turn-offs. It's purchasable with roughly 7,000 aspiration points. As with all aspiration rewards, try to use this item with a gold Aspiration level or you might end up with the Grilled Cheese aspiration. This item is only available in the Nightlife expansion.
Also, after you pass your sophomore year in college, your Sim can change aspirations. Of course, this is restricted to the University expansion.
Yes, it is possible to change you Sim's aspiration.
There is an Aspiration reward called the ReNuYuSenso Orb available for 6,250 Aspiration points. It will allow you to change your Sim's aspiration as well as turn-ons and turn-offs. It only has 5 uses in it though.
Do note that if you use it with your Aspiration level below gold, your primary aspiration may be changed to "Grilled Cheese", which will make you obsessed with grilled cheese sandwiches.
If you have the Free Time expansion, it can also change your secondary aspiration and your aspiration benefits.
If you have the University expansion, your Sim can change its aspiration after its sophomore year, but that may not be what you're aiming for if you already have a wife and kids.