Just dig the poor thing up. You'll probably find it easiest to cut most of the branches back so you can get at it. Leave about 6-8" for you to get hold of. I don't think it'll give you any problems coming back, and back, and back.

You've nothing to lose if you take some of the branches, preferably non-flowering ones, poke them in the ground in a shady spot and see if any will root. Then you'd have a smaller version (and maybe some spares to give away) of what was once a pretty good plant, probably, before it got too big.

If it is too big, why not just trim the whole thing back? You have been cutting it back every year, haven't you? I would trim it by half in the fall and finish the job next spring when the new buds appear.