Switching from Micro to Nano SIM but keep old number?

I'm on a prepaid account ($25 per month) and I have a micro SIM card. My current phone is a Windows phone that I bought around 3-4 years ago. If I had my way, I wouldn't get an upgrade; however, i'm now in a situation where i'll need a phone that can access various apps that do medical calculations, etc. that are only available on actual smartphones. 

Obviously, all the modern phones use nano SIM cards. I know that you can allegedly just cut down the micro SIM to fit into a nano SIM slot but I honestly don't feel really comfortable doing that and would prefer to simply have my old number (on my micro SIM) transferred to a nano SIM card; however, I do not know if this is even possible. Honestly, I doubt it but I thought I should check here first. So, my question is: Can I switch from a micro to nano SIM card on a prepaid account and keep my old number?