Small improvement in remapping

[AndyZe]

Resizing this output vector with every iteration isn't necessary.

The idea here is, make the variable static so it retains its value between iterations. Only remap if the dimension of the vector changes.

Partial fix to #392

[AndyZe]

well, this method is actually called in the update loop. I'll probably end up closing this PR if dof_ becomes constant because it won't be relevant anymore.