back the Gaxaxywatchdesigner\keystore folder up first
Going on memory here
I believe the certificates you generated with Tizen has the same .p12 files .csr and password files in that folder.
I think you can then just replace the files in the GWD\Keystore p12 files with the new ones you generated. If for some reason that didn’t work i.e. you changed the password try replacing all the files from the new Tizen Studio keystore folder into the GWD folder.
Let me know how this works. In theory it should work fine.
Ron
Samsung Developer Relations