Vaginal atrophy and associated symptoms will always return as soon as treatment with oestrogen etc is stopped. If you are still getting bouts of pain and problems then your dose is insufficient and as the others have said - maybe you need a re-load, or a higher dose all the time.
There are women on here who need treatment in between the oestrogen to keep things lubricated - eg with Replens like you have been given, and other products (more suitable ones than KY). There have been posts about this recently and there is the Burning Club thread too in Private Lives. I can't help here as I only use vag oestrogen. The Estring delivers a higher dose of oestrogen. Dancinggirl and Maryjane are the members with most knowledge and experience about this ie what other products to use so perhaps have a look at some of their posts?
Re your comment on oral HRT - you don't have to take oral HRT to use systemic HRT. Many of us use transdermal HRT - ie patches (or gel) and maryjane is one who has this and local oestrogen just to control VA, so perhaps something to think about if additional vaginal treatments don't work. Transdermal route of HRT is recommended for those who suffer from migraines.
Hope you see an improvement soon but do think about increasing your vaginal oestrogen as well and especially that re-load!
Hurdity x