I found the problem, and I found the solution. Along the way I found a reference to Sys.getenv and Sys.setenv (in the base package). I ran Sys.getenv and found that the R environmental variable R_LIBS_USER had been set to the old path. So I ran:
Sys.setenv("R_LIBS_USER" = "c:/larry/r/win-library/4.1"))
pointing to the new library and this fixed the problem for all of my workspaces. Of course, change the second quoted string to your own user lib, and if your OS is Windows, as mine is, be sure that you use forward slashes to separate the folder names.
Larry Hunsicker