Just because you can see roots coming out the bottom of the pot does not mean a plant is rootbound. How tall is she at the moment? Has she been transplanted before?
To me, its a bit of a gamble whether to transplant or not. If youve done it before and are good at it, then go for it. If youve never done it before, then leave her be. Also, if shes been transplanted before, then leave her. If you do transplant though, Id use Superthrive considering shes flowering.