Hello Sukhvir

Repeating class 11-12th with a different stream.. it's a big decision. If you're completely sure that you can focus on science field by studying subjects Physics chemistry biology which will be new for you.. then only go for it. You have to determine yourself for this. Because Science is completely different and the field from which you've passed is completely different. So decide accordingly.. as commerce has a lot of fields n careers further. You can learn a lot n can get good job even. Discuss about your decision with your family and then take any step.
And yes, you can get admission in 11th Science on the basis of your 10th result.. but you need to keep your results of 11-12th commerce ready for the document submission if asked during the admission in 11th Science.

Hope this helps.!
All the Best !!!