You may want to trim it way back, and give it Hollytone or other acid-loving plant food. My rhodo was probably as old as my house (built in 1968/9). The last few years it got rather scraggly, and didn't produce many new leaves. Flowers were down somewhat, too. This past winter was terribly harsh on it, and I cut out about 2/3rds of very dead limbs before I thought to take a photo. (Photo dated 4/15/15) I considered removing it entirely, but I'd need a backhoe to remove the roots, and I plan to sell here within the year.

About a week later I realized scraggly wasn't going to cut it, so I CUT it... The leaves at the base were still viable. So I cut it down, leaving the base. I still have to remove the thick stem at the back but it's tough wood and I only had a hand saw at the time. (Yes, and the stonework path is being renovated & tidied up this year, too.) This next photo is dated 5/24/15, and you can see the really vibrant green growth! Only one flower but I cut off all the upper buds, so oh well for this year! Next year's owners will have a chance at a vibrant rhodo!!! I haven't seen so much young green leaf growth on this plant for years!

wow thats good to know. I have few rhododendron bushes which look similar to yours. may be after it is done blooming i will give it a trim. do i have to fertilize after trimming or later next year?