This is the method I've use and this has always worked well for me. I found this online somewhere so I can't take credit for it. Merely passing it along.
You will have to re-allow any apps that you had previously granted SD Card permissions to but besides that it's pretty easy.
"Unmount the storage card from you phone (Settings —> Storage —> Unmount SD card)
Turn off the phone, remove the back cover, and carefully take out your current microSD card.
Slide it into an SD-adapter and then slide the adapter into your PC
Using Windows Explorer find your card listed among the available drives and make a note of the drive letter assigned to it (in my case it was F, but depending on your setup, it could be G or some other letter).
Click on the Start button on your desktop.
In the search window, type: Command Prompt — and then press the Enter key to open the Command Prompt window.
Enter the following commands (pressing the Enter key at the end of each line):
cd /
md sd-card
cd sd-card
xcopy F:\ "*.*" /s /e /v /h
The first command above changes the current directory to your root drive.
The second command creates a new folder (directory) in your root drive named “sd-card”. (You can use any legal file name here, but you must remember to substitute that name in place of “sd-card” in the code below. If you use spaces in your new name, then you must put double-quote marks around the new name.)
The third command changes the current directory to “sd-card”.
The fourth line is the key line. Make sure you type exactly as shown. In this line, I have used the drive letter F, if your system assigned a different drive letter for your card, use that letter instead of the F. (Remember also, if you used a different name than “sd-card” for your folder, you must use the new name here (with quote marks if you have spaces in the name). The quotes marks around the wildcard characters (*.*) is what tells windows to preserve your long file names. (Not that Microsoft bothers to tells you that in any of their documentation that I found.) The letters at the end this line are called switches and tell the system how to copy you files: /s copies folders and subfolders except for empty ones; /e copies any subfolder, even if it is empty; /v verifies the copying; and /h copies hidden files.
It may take several minutes to copy the files from your current card into the sd-card folder (or whatever you have named it).
When the copying is complete the systen will tell you how many files you have copied.
Remove your micro card adapter from the computer and then carefully remove the micro card from the adapter.
Now insert your new micro card into the adapter and insert the adapter into your computer. The system will assign it a drive letter (almost always the same letter as before — but it could be different, so check to be sure).
In the Command Prompt window, type in the following, hitting the Enter key at the end of each line:
cd /
cd sd-card
xcopy "*.*" F:\ /s /e /v /h
As you are typing the above, make the necessary substitutions if you are using a different name for the folder, or your drive letter is different.
After the files have been copied onto you new card, remove the adapter from your computer, and then carefully remove you new card from the adapter.
Carefully insert your new card into your phone, replace the cover, and start your phone.
You will find all your apps, pictures, movies, text messages that were stored on your old card are now on your new card."