Anemones just like people don't heal overnight, just because you have now added better lighting doesn't mean it will add instant health.
Its normally a sign of stress if its mouth is gaping like that, sometimes for other reasons.
Are your water paramiters staying stable?
Pay attention to your pH value as well.
If it is suffering from a loss of its zooxanthellae then it could take up to three months for it to be recovered.
If it is suffering from acclimation shock, pH shock, or even lighting shock then you will just have to give it time to recover.
I would try to feed it once a week, maybe twice. Keep your water paramiters where they should be. Keep up with the water changes if necessary. Run fresh carbon once every couple of weeks for a while.
What photo period are you using on these new lights?
Thomas