The easiest way to make a Bled trip feel more varied is to stay in one place and change the landscape during the day.
For another lake
Lake Bohinj is the clearest contrast. It feels less polished and more connected to the national park.
For forest and mountain access
Pokljuka is close, cooler in summer and useful even when you do not want a full hike.
For easy dramatic scenery
Kranjska Gora combines well with Jasna, Zelenci and the road toward Vršič.
For a shorter outing
Vintgar or Radovljica can fit into part of a day.