my Bonsai Tree

look at my Bonsai tree! I am trying to get soil to repot it, i do have Cactus soil: fav.me/d7gzhi6m, but idk if its ok to use on my bonsai. 
the pic on the right is after i got it and it wasnt until after winter was over which was long that it started to turn crunchy and brittle.  water it ever 2-3 days or when it needs it. I am trying to get soil if i cant use this soil i have. I want to trim the roots, since i read on a Bonsai tree care site that its something that you can do. 
if anyone has any suggestions on what i can do that'd be great. unless theres nothing i can do, but i dont wanna give up on my bonsai tree.