How can I prevent droopiness after eyelid surgery? (photos)

I have had a successful and conservative eyelid surgery to fix the assymetry between my eyes. Even though i liked the results ,my doctor notified me that because of my forehead i will get droopy eyelids again. What does he mean? Can someone perform blepharoplasty twice? Do you recommend any procedures to prevent this, like forehead botox?(doctor is retired now so i cannot get advice from him)