I'm a 4th year student in a university in Canada, studying pure math. My GPA so far is barely about 3.0/4.0. I was young and totally screwed my undergraduate years. I have planned to go to grad school right after I graduate, but these days I feel so regretful about my GPA that even makes me want to repeat it again in some other university(maybe in some other program too.) With my GPA, I will end up with getting into very minor graduate school. But if I spend 4 more years for another undergraduate program, high GPA is almost guaranteed(which also suggests that I could get into top grad schools.) As my ultimate academic goal is being a professional mathematician, receiving education from well-known institution seems very important to me. But I still wonder if it is worth another 4 years of my life and the money it costs. I appreciate any advice. Thank you.