Hey there,
Come up with a short list of schools you would like to apply to and take a look at the average GMAT score of their incoming class, which will be a good indicator of whether you should retake your GMAT. Since your performance in school could be below average for some schools, you should shoot for an above average GMAT for certain schools to make up for it. Keep in mind that international opportunities for schools in Canada or Europe after school are more limited than those for schools in the US have to offer. If you're intending to stay in Canada or Europe after school, then do some research for schools in the top 10-20 assuming you can get 600+ on the GMAT. Hope this helps and good luck!