Weight Mirroring problem

I am having trouble getting my weight groups to mirror across a body. I have been tweaking the weights on a body that is set up with Left and Right versions of each vertex group (So, Bicep.L, Bicep.R, etc.) The body was made with Makehuman.

So far, while working on the weights to get the deforms I want, I have been letting it automatically mirror on the X axis, so if I change Bicep.L, it automatically changes Bicep.R. However, I did something or other that caused it to no longer consider both sides of the body to be symmetrical, causing mirroring to break.

To get the mesh symmetrical again, I used the Symmetrize tool under the Mesh menu in edit mode. This fixed the mesh symmetry problems just fine, but it messed up my vertex groups. Now, the Left side vertex groups have the painting on both the left and right side of the body, and the Right vertex groups are all empty (presumably because the Symmetrize tool copied the left side over the right side.)

I need a way to get my vertex groups set up properly. I can do it longform by copying each vertex group, changing the name from .L to .R, and then deleting the redundant weights from the left side of the model. However, I am posting to see if there is a more efficient way to fix this, or some command/tool that can do this all automatically. The Mirror Weights tool in weight painting mode and the Mirror Vertex Groups tool don’t seem to be working.