Every time I am havingtake a break after studying for several hours, my parents ask me why I am not studying and tell me to do it.

"take a break" is more colloquial. It sounds more natural.

"studying several hours" isn't exactly wrong, but it doesn't sound right, either. [for + period of time] is more correct.

In such a case, I go back to my room and start studying again, so that they will not think that I really am a lazy person.

You can also say:

"so (that) they will not think I must be a lazy person"

"so they will not think (that) I am lazy."

"so they won't start to think I must be lazy."

You don't really need "that" in this sentence, but it's not wrong to use it. Using "lazy" by itself also sounds more natural.

Every time I am havingtake a break after studying several hours, my parents ask me why I am not studying and tell me to do itstudy again.

These are some other phrases to replace "to study again"
"to get on with it"
"to get back to it"

In such athat case, I go back to my room and start studying again, so that they will noey don't think that I really am a lazy person.

Every time I am havtaking a break after studying for several hours, my parents ask me why I am not studying and tell me to do itstudy.

In such athis case, I go back to my room and start studying again, so that they will not think that I really am a lazy person. ¶
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You can also say "...that I am a really lazy person". It depends on what you what to emphasize.