To trim back a weevil-afflicted ivy or not?

As recounted at the link given below the photo, we have beaten a fierce army of vine weevils this year by placing a two-inch layer of stones in the tops of our planters of laurel bushes, but unfortunately we didn't add a similar layer of stones to a nearby ivy bush at the same time - because in previous years the weevils completely avoided the ivy, presumably because they prefer eating the leaves of laurels rather than the leaves of ivy.

So six weeks ago we discovered the leaves of the ivy shown below to have been badly nibbled by vine weevils, dozens of leaves had turned brown (but were still attached to the plant), and several dozen other brown leaves had fallen to the ground (where we found weevils sheltering under them during the day).  We immediately shook all the weevils off, cleared away all the dead leaves and bark chips from the top of the soil, and put down the layer of stones. 

But although for the last six weeks we have seen no more weevils on or near this ivy, unfortunately there has been no new growth on the plant and many more leaves have slowly turned brown.

There is clearly still life in the plant, otherwise all the leaves would have turned brown.  We think that the weevils laid eggs before we noticed their presence and those eggs may have hatched and the young may have badly eaten the root system (as developing weevils do), and, worse still, those developing weevils may still be munching away at the root system.

We think this bush is struggling. 

The obvious solution is to do what we did with the laurels (trim the bush right back, leaving just a few runners of about a foot in length), to enable the bush to sprout efficiently next spring. 

We've tried drenches and nematodes repeatedly in the past and found they don't work. 

So before we do another heavy pruning, I thought I'd ask for people's experiences in similar situations.