How do I reset previous project from 44.1k to 48k?

I'm working on some video post production stuff.  The audio files used to play for the recording were done at 44.1k, but the video was recorded at 48k.  Most of the original music was midi-based in Sonar with Kontakt and other soft synths.  I need to remix some of the files.  Is there a way to change the project settings for the original files to 48k then re-record or re-freeze the synths and still get the 48k?  I know I can create a new project file with the default set to 48k, but I'm hoping there is another way with few steps.
 
The reason for doing this is when I import the original 44.1k audio files into the video editing software, the timing drifts after awhile.  With a test audio file (the timely method) converted to 48k, things stay in sync.
 
Thanks for the help.

Nice one Sanderxpander. 

I think I spoke too soon.  Here is what I've learned in the last 24 hours:
1.  If a project was created using the 44.1k rate set in preferences, all software synths will use that setting.
2.  Deleting audio files of one sample rate and replacing them with the new sample rate creates something really unstable since somewhere the original sample rate is written in the file.  (ask me how I know,...)
3.  I can export the wav files from Sonar into a different format, but there is little guarantee they will time-align when reassembled. 
 
It appears that even a simple midi-only file using soft synths will need to have the tracks copied into a new file with the required sample rate.  I was hoping there was a dialogue box somewhere that would let me change the properties of a file so that all synths would magically switch to the new setting.
 
I will try to use the time-stretch feature to align exported files to the video file.
 
Thanks for the input.

gbarrett
2.  Deleting audio files of one sample rate and replacing them with the new sample rate creates something really unstable since somewhere the original sample rate is written in the file.  (ask me how I know,...)
 

That's really weird. I personally used the replacing files's sample rate method quite a few times back at X2 days and never had any problems with that. All those projects had a bunch of softsynths in each one too (including Kontakt). Could you elaborate on that "really unstable"? Because there is a chance the whole instability thing could be caused by your audio interface which is having troubles locking to 48 on the fly and back (like my Fast Track Ultra, which can even BSOD sometimes for that matter if I try to switch rates when something like a music player is set on pause in the background or a browser window is opened with Soundcloud or something).