My question involves marriage law for the State of: Illinois

Divorced 5 years ago. Court ordered that I pay my ex $1500 a month because she is disabled (she also gets social security / long term disability) and I have a decent paying job now. I'm retiring in January. Once I retire, my montly income will only be 1100.00 after I pay her. She will be netting about $3000 a month. Is there a way to take her back to court due to the income difference when I retire and the difference in what I will make then vice now? Don't really mind paying now, but later seems so unbalanced. I will always have to work to be able to afford to pay her at that level and live myself.