I'm trying to put file my IL state return. I've tried to e-file, using the AGI from last year , but it got rejected. I'd prefer not to mail it , but is that only option ?

If you have corrected any rejection errors, and if you are using the correct AGI, and it is still being rejected the you will have to print and mail your return.  It's not an ideal situation, but sometimes there is no other option.