I have had the experience where I fasted to see change in my spiritual life, but after Jesus answered me I would at some point return to struggling in my walk again. Has this ever happened to you?

What I learned is, those principles that we practice when we are fasting should carry over into our daily walk with Christ. For example, when a person is truly fasting they are careful to avoid sin. Also, they are prayerful and they are thinking about Jesus more than they are thinking about other things. These are all principles we should practice daily to nurture our relationship with Jesus. That is how we will maintain our progress. 

A person who is only applying those principles during a fast will always be up and down in their spiritual state. They will be high during a fast when they are seeking God and obeying Him, then after fasting they will be down again because they became distracted from Christ or are doing other things that displease Him. 

Fasting is an important part of our walk with Jesus, but it will not benefit our spiritual lives unless we continue being careful to walk in God’s ways. 

Proverbs 21:3 says:
To do justice and judgment is more acceptable to the LORD than sacrifice.