Changing audio format mid-project 44Khz to 48Khz

I am in the middle of a project, which is at 44Khz. Its mainly soft synths, some of which I have bounced to audio, and some pure audio tracks.

I find out now I need to finalise as a 48Khz stereo wave file. Can I just do the conversion at final Export? Or should I convert each seperate audio track to 48Khz first? Or do I need to re-do the recording for each track at 48Khz?

Leave the project as is and export the final mix to 48k.