u/GullibleLeg7604

Anyone have any ideas on what's causing these yellow spots on my draceana? I've had the plant for 6 years and noticed that a lot of the leaves were turning yellow/brown last year. I have repotted with new soil about 6 months ago and initially the new growth was green but it's now turning speckled again. I water it every 2/3 weeks so don't think it's an overwatering issue and I use filtered water. The plant is near a window and gets plenty of sunshine....any ideas of where I'm going wrong?