Okay, then don't water as often.
When you water you want to drench the pot, until water runs free out the bottom drainage holes. Then you let the pot approach dryness. Dig your finger into the pot, at least to the base of your fingernail, if the media feels cool and damp, don't water. If the media feels dry at that depth below the surface, you should have watered yesterday. Ideal is allow the media to dry to the "just barely moist level, then water. Each watering should be thorough, flooding the entire surface of the pot with water, water heavily enough that water runs out of the drainage holes in the bottom. Then allow the pot to approach dryness.
Each time you check for moisture, notice the weight, or heft, of the pot. Dry soil is light, wet soil is heavy. Soon you will know if you need water just by noticing the weight of the pot.
You did not mention what species of tree your bonsai is. Each species has its own requirements, some like more water, some like less water.
Without knowing what species of tree you have I would not repot, some species tolerate summer repotting, some species do not. Slip potting is a bad technique, as often slip potting is a traumatic for a tree as a "formal repot". Better to hold off repotting until the proper season and then do a proper repotting.
So adjust your watering to the tree's schedule. Use the actual feel of the potting media to decide when to water. My indoor trees seldom need water more than once every 4 or 5 days depending on temperatures. My outdoor trees need water anywhere from daily to every 3rd day depending on weather. And if we get rain, I water less often outdoors.