Your lily may be suffering from over watering, unnecessary/inappropriate fertilizing and still being attacked by spider mites.
Yes, remove the dead flowers and yellow leaves. Start watering the plant only when the top 1 inch of the soil feels dry to the touch. Make sure that the pot has good drainage holes in the bottom of the pot.
Don't fertilize the plant for at least several months. Most commercial potting soils have enough slow release fertilizer pellets that can provide enough fertilizer for the plant for at least 6 months. Fertilizing a unhealthy plant won't cure it, it will actually cause more harm. Over fertilizing a healthy plant will just make it a unhealthy plant. Fertilizer should be used very sparingly in potted plants during times of healthy, vigorous growth.
I am pretty sure that the plant still has spider mites. I never recommend using just plain alcohol water. Straight alcohol is very useful in getting rid of a single or small number of insects, such as mealy bugs, but alcohol by itself is not very effective in getting rid of large populations of spider mites. The alcohol dries too quickly to get good coverage on a lot of mites. Best way to deal with spider mites is to mix a few drops of Dawn dish liquid and distilled water in a spray bottle. Spray the plant thoroughly. Be sure to get all stems and both sides of leaves. Repeat every 3 days for about 2 weeks, until all signs of spider mites is gone. If spider mites are persistent, I will add a couple of teaspoons of alcohol to the soapy water spray. The soap in the water keeps the alcohol from drying as quickly and it is more effective.