Is it okay to keep making the same dua for years?

Persistence is part of dua

The Prophet ﷺ said: "The supplication of every one of you is granted if he does not grow impatient and says: I supplicated but it was not granted" (Sahih Muslim 2735). The only thing that "cancels" a dua in that hadith is quitting. So asking for the same spouse, child, job, health or guidance every day for years isn't nagging Allah. It's exactly what He loves to see.

Prophets waited too

Prophet Zakariya asked for a child into old age, and said, "never have I been in my supplication to You, my Lord, unhappy." Prophet Ya'qub waited many years to see his son Yusuf again, and still said, "I only complain of my suffering and my grief to Allah" (Quran 12:86). Their duas were answered, but on Allah's timeline, not theirs.

Your dua is never wasted

The Prophet ﷺ said that whenever a Muslim calls on Allah, "Allah grants it to him, or he turns away from him the like of it in evil," as long as the dua isn't for something sinful or for cutting family ties. When a man asked, "What if we should increase (in it)?", he replied, "(With) Allah is more" (Jami' at-Tirmidhi 3573). Other narrations add that the reward may be saved for the Hereafter. Either way, every repetition counts.

Keeping it healthy

• Ask for what's best: add "if it is good for me" to your dua. Years later, many people are grateful a certain door stayed closed.
• Take the steps: dua and effort go together. If you're asking for a job, keep applying; for marriage, let people know you're looking.
• Use the best times: sujood, the last third of the night, and between the adhan and iqamah. See What are the best times to make dua?
• Watch your heart: if waiting turns into bitterness or despair, talk to someone you trust, and get professional help if it's affecting your mental health. See Why isn't Allah answering my dua?