Reset Life (2019)

Both have time travel involved. In Closer To You, the male lead is transported to the past to save the life of his friend. In Reset Life, the female lead is transported to the past and is able to accomplish great things after having found out what happens in the future. In Closer To You, when he gets transported to the past, there is no "returning to the future". Instead "whoever" gets transported to the past they live their life until the present day. Let's just say this may or may to happen to multiple characters. If you are looking for a simpler version of the Chinese drama Closer To You, I urge you to watch Somehow 18, Korean drama.

Both involve time travel.
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This drama is also about time travel. The ML of future time contacts with past version of FL through a phone. He fixes all of the messes by contacting with FL.

FL returns from her unhappy present to her school days and tries to fix the events of the past including stopping the death of a loved one.

Both are Chinese mini dramas with a love story based upon time travel and changing fate.
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Both have romance and a mom who is dead in the future who the female lead tries to save.
Go Back Couple is about a married couple and wanting to go back because of marriage problems and it also tugs more at your hearstrings while Reset Life is a more lighthearted version of Go Back Couple. Both are well crafted dramas that don't drag at all. Both short and sweet. Go Back Couple is 12 episodes while Reset Life is 5 episodes. Go Back Couple obviously has more depth since it has more episodes to develop it but nonetheless both are amazing dramas that you must watch.

FL returns from her unhappy present to her school days and tries to fix the events of the past including stopping the death of a loved one. Sweet romance between leads. Short length dramas.

Both are mini dramas with one of the leads traveling to the past to save someone. Both have a school setting in the past parts.

Both are mini dramas in which one of the leads time travels back to their school days in an attempt to save a loved one who died back then.

Both are mini dramas and involve time travel.
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Both are short dramas in which the FL travels back in time and attends school alongside the ML. Both dramas have a similar feel and tone.

FL time travels and returns to her younger self and falls in love with the ML. Both FLs then try to undo a death (FL's mother vs. ML's). Both are school setting. The FL has met the ML in the past but doesn't know/remember it until much later after she time travels.

Both FLs time travel to their school days in an effort to save someone.
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Both dramas involve time travel and trying to change fate to prevent death(s). Both have a subtle romance between the main couple.

Both female leads get a second chance at their teens. The question is will they be able to change what happened in the past?