If you use strategic redeployment you will change the supply base for units in remote areas even if you redeploy them back to their original locations. It will of course, cost seven-days movement time plus the time taken to recover lost organization.
HOWEVER
I have had mixed success doing this, in a recent TGW game I used this technique for a couple of French divisions in Budapest which I have taken from Austria-Hungary and which were supplied from the port of Split on the Adriatic Sea. Their new supply centre is Cernowitz, a province in Russian hands that is closer geographically but without a land supply line free of enemy units. The net result is that I'm worse off then before. Can't figure that one out and have not been able to determine what drives the selection of a supply base when strategic movement is conducted in conquered areas. I had some success using this technique to shorten my supply lines while conqueroring the Ottoman Empire but in Central Europe...
Also, when transports disembark troops over beaches, they retain the original port of embarkation as their supply centre which can lead to horrendous penalties when conducting trans-oceanic operations. However, units that are unloaded directly into a friendly port seem to adapt that port as their supply centre. Embarking distant supplied units and then immediately sailing them back into port seems to reset their source of supply to the new port and reduce the combat penalties considerably.
This is probably not what you wanted to read but it's the best I can come up with right now. Good Luck.