How about if they just feel they are not leading a Christian life?
What I am getting at is Catholics would use the sacrament of penance if he/she believed sin was excessive, there does not appear to be a parallel in protestant thought. I’m guessing once saves always saved would make this unnecessary.
We believe that Christians who fall into sin are convicted of that sin by the Holy Spirit and are called to repentance. When this happens the person will often confide in a pastor, relative or close friend that they are under conviction and will get counseling in how to overcome the sins they are struggling with.
For instance, if someone is watching porn and comes under conviction they will often go to a pastor and enter into counseling. This is done privately and the members of the church are not alerted to what is going on. This also happens with marriage problems, alcoholism and so forth.
There is no formal process of penance, like within the Catholic church. Our pastors don’t say, do something (Hail Mary’s or whatnot) and you will be absolved of you sin. They say, stop doing what you are doing and pray to God, confessing what you have been doing and ask Him to change you and make you more like Him. But we understand the God uses counseling, doctors, friends and family as well as the Bible and the Holy Spirit to shape us and mold us and make us more like Him. Sometimes there is a miraculous “God took the sinful desire away from me” moment but most often the fight against sin is a struggle and we, as the family of God, are all enlisted to help each other deal with that struggle.
The Baptist church is about community and we do our best to bear each other burdens, help each other overcome sin, and encourage each other to live a life worthy of the Gospel.
But to finally answer your question

, no, if someone feels they have drifted away from God then they aren’t re-baptized. They are encouraged to repent and confess then worship and serve and seek the Lord with all their heart.