my hebe is losing its foliage

Not sure what you're asking, need more info or a picture?

It could be caused by vine weevils which are small white grubs ( larvae of a kind of beetle) that eat plant roots.

If that is the case by the time a person realises there is a problem often too much damage is done and the plant can't be saved.

However I'm not sure if there are particular plants that they go for or not.

If the plant is in a pot if it is waterlogged this can cause the plant roots to die as well. I need to sort out one of my plants where its roots have now blocked the pot drainage hole and the pot doesn't drain properly. It is surviving for now but not very happy and I suspect it must be quite tolerant of wet conditions.

Can you give more information about your plant - how long you have had it, what conditions it is growing in etc?

I've had this happen with a lot of my Hebes.
I think they are best for an annual pruning otherwise left longer than a couple of years they get leggy and can lose leaves.
I've cut mine hard back and by that i mean to about 6 - 8" from the ground and each time they've been rejuvenated. (these were all low growers to no more than 2' tall)

You could try that and see what happens, it sounds like you've not got much to lose.

(would love to know how it goes on too)

Don't forget drought either - it has been very, very dry in London and the soil is like dust, even after the recent rain.

Same here Mims, dig down 5 or 6" here and it's bone dry, i live on a hillside so that doesn't help at all either.