This entire day could be dedicated to explore the beaches on the southern part of the island- from Balangan to Padang-Padang. Towards the end of the day you can enjoy the sunset from Uluwatu, while watching the traditional Balinese Kecak Dance. They have a daily performance at 6PM.

1. Beach hopping- among the best beaches in the area include:

a. Balangan:

b. Dreamland:

c. Padang-padang beach:

2. Lunch at Pecatu: 

You can visit one of the most luxurious and beautiful hotel in the island, Bulgari Resort and Spa, and have lunch at Sangkar Restaurant overlooking the ocean.

Other restaurants in Pecatu:

Kelly’s Warung (Indonesian), Warung Bejana (Indonesian), and Trattoria (Italian).

3. Uluwatu Beach and Uluwatu Temple:

You should allow plenty of time for the car journey to Uluwatu in order to visit the temple on the cliff, and then enjoy the Balinese Kecak Dance while also watching the beautiful sunset. 
I would probably start relaxing a bit on Uluwatu Beach, possibly for a quick swim in the ocean, or for a cocktail in one of the beach clubs.

Latest by 3.30-4PM, you should start your journey up to the temple on the cliff.
    
Uluwatu Temple (or Pura Luhur Uluwatu) is a Hindu temple built around the 11th century at the edge of a 70-meter high cliff projecting into the sea. This temple is believed to be one of the sad kahyangan (heaven) and was dedicated to Sang Hyang Widhi Wasa in his manifestation as Rudra, the God of the roaring storm. 

  
There are two entrances to this temple, from the south and the north. Also, there is a forest that lies at the front and hundreds of monkeys who dwell there are believed to guard the temple from evil. The view of the ocean from the temple is magnificent. Furthermore, the locals believe that the three divine Hindu powers of Brahma, Wishnu and Syiva become one here, resulting to making this a place of worship for Syiva Rudra, the deity of all elements and aspects of life in the universe.

Right around the temple they have a daily performance of the traditional Balinese Kecak Dance that starts at 6PM (please check if there are any changes to the schedule). You can also watch the beautiful sunset from here.

Created in the 1930s, this dance and music drama has been performed primarily by men. It is also known as the Ramayana Monkey Chant, performed by a circle of at least 150 men who all wear checked cloth around their waists. They all percussively chant “cak” while moving their hands and arms, depicting a battle from the Ramayana, of the good Prince Rama against the evil King Ravana, helped by the monkey-like Vanara led by Hanuman. This is a very interesting dance and is believed to have roots in sanghyang- a trance inducing exorcism dance.

4. Seafood Dinner in Jimbaran:

Then you head out to Jimbaran Bay for dinner. My first choice would be Café Menega, where they offer a variety of fresh seafood for you to choose, and you can enjoy your dinner right on the beach. The food is very good.  And please, bring your own wine.

Other restaurants in the Jimbaran area:

Sundara (Four Seasons Hotel), Jimbaran Bay Seafood Club, Unique Rooftop Bar (Mexican), and AKUA Bali.