What's the correct way to load a new set of metrics/horizons?

What's the correct way to load a new set of metrics/horizons?

What's the correct way to load a new set of metrics/horizons? i.e. if a
user were allowed to choose from a list of metrics in a multi-select.
Right now, I have a working implementation that simply runs
d3.select('#graph1').html(''); and reruns the horizon setup
d3.select("#graph1").selectAll(".horizon").data(my_datum.map(load_metric)).enter().insert("div",
".bottom"); BUT this seems to cause all previously loaded to to disappear
from the horizon after an incremental set is loaded.