You have placed candles on the bottom front of the fireplace so try taking away the candles on the top mantle of the fireplace.

Love the plant and the wall hanging. Not sure about the blue but I would try clustering the 3 different sizes of blue accessory at the end opposite the plant and remove the 2 other blue items and the other (red?) item. @216Sharon on twitter

The dark metal of the clock on the light wall as well as the dark mantle shelf, make the room appear shorter. The cabinet color clashes with the dark wood causing it to feel a bit disjointed. Also with so much on the mantle and the "Family" word art on the oak cabinet, the left side looks very bare. The ottoman is too small to make up the design differential.
But you can do a couple of things.
1. You could paint the dark wood mantle shelf and oak cabinet the same color such as an antique white.
2. Or: Paint the brick an antique white (a lot of people would have strong opinions about this, both for and against) and leave the mantle dark, but paint the oak cabinet the same dark color as the mantle shelf.
3. Either way if you can, purchase an additional cabinet for the left side to balance the fireplace and paint it whichever color you ultimately choose. If you can't, try to balance it out with a tall piece of wall art like a painting.
4. If you paint the wall a deeper color such as a pale teal, you'll warm up the feel of the room.

Terri, the cabinet on the right is coming out of the room and the wall is Benjamin Moore winter gates, I also used reds see photo

The blue accessory really brighten the room.( My personal prejudice- I love blue.) seriously the cool blues balance all the warm tones so add a few more in pillows or throws. Angle the chair in the corner with a tall floor lamp and something on the wall. Maybe move the clock there and add a mirror over the mantel If you keep the big clock above the mantel lower your candles to plates instead of the large holders. Try switching "FAMILY" to the mantel with just a couple candles and putting the other stuff on the cabinet. Fewer accessories and a smaller clock would make the ceiling look taller

Karen I like the red clock and candles. Put the plant on the hearth and group candles closer to the clock. It will make a more triangular arrangement.

What if I remove the clock and add a large mirror with a thick silver frame?

Yes, too much stuff. I would get a long (about the width if the firebox) horizontally oriented piece of art for the center. Then some thing on either side, not candles since you have those below, and you will be done.

Karen - you gotta' love how our computer monitors can distort color. I would never have guessed it was Winter Gates! I do think trying out a mirror would be a good easy start. I prefer the blue accessories over the red, party because the gold sofa works better with that color coming into the spring, but you could certainly change it back to red for the fall. Also grouping smaller items, but placing them at different heights looks better sometimes than trying to be symmetrical.

Lighting is part of the issue here. The ceiling spots are causing a deep shadow to be cast under the mantel and are visually doubling its size. They are too close to the wall and if properly placed would illuminate the front of the mantel and FP. Changing them is a big job, but maybe if you lowered the wattage the shadow wouldn't be as harsh. Personally, there are 3 places for clocks - bedside table, bathroom, and kitchen - all where they can keep you on time for work and appointments. As decor, they suck. If you haven't already done so, start an ideabook for yourself on fireplaces to see how its done. One major point is keeping the items closer to the mantel than to the ceiling. The space between mantel and ceiling looks to be extremely short and therefore limiting. That said, try treating it more like a shelf than like a mantel. Here's a thick linear mantel with a simple row of books, bookends, a bell collection and a propped picture. Then a second one with linear candle holder, glass jugs and twigs. Either one can work better for your situation. Remember to keep grouping os items in pairs together or in threes & fives.