Can we add subject 'you' in the imperative sentence?

Question

Can we add subject 'you' in the imperative sentence?

Without studying regularly, don't expect to get high marks.
→ Without studying regularly, you don't expect to get high marks.

Answer 1

Without studying regularly, you don't expect to get high marks.

By putting you in the position that you have, you have changed the sentence from the imperative to the indicative.¹ The you here is the generalized you that means one or a person.

To maintain the imperative mood, you could put the you after the don't to get

Without studying regularly, don't you expect to get high marks.

However, this is highly stylistic/stilted/possibly old-fashioned. In other words, it would not be common to encounter it in everyday English.

One the other hand, "don't you forget" about this song:

Don't you (forget about me) (YouTube video)

Here, it's usage in art does not indicate common usage in everyday English; it just goes with the rest of the song in wording, style, rhythm, stress, et al., but the imperative mood is easily recognizable by the native speaker.

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¹ This is the case if you read or say the sentence normally without any unusual stress on you. Even if you stress you, you are still in the indicative. But if you "separate" you from the flow of the sentence, and turn it into the vocative you (calling out to the person "you") , as in

Without studying regularly, you! (you there!)(hey! you!), don't expect to get high marks.

then you have an imperative.

Answer 2

When you insert a you, you have to change the verb to can't:

→ Without studying regularly, you can't expect to get high marks.

But it is not an imperative sentence anymore, it's just informative then.