This question could be surveyed from two different aspects:
As the initial aspect it would be said that solely praying (dua) for the highest point in Jannah won’t be sufficient. Since you should have good deed to be hopeful that Allah takes you to the highest points… otherwise as a rational rule, Allah won’t give us high point without having good deeds (just to say it by our tongues...)
On the other aspect, we should be hopeful regarding the promotion of our high-point, since Allah has declared in the Holy Quran that “Call upon Me; I will respond to you”, consequently it indicate that pray (dua) would be effective in granting the desires and needs that Allah himself mentioned it. Anyhow we should be hopeful about anything along with having good deeds.
Look at the following verse of the Holy Quran which could be related to your inquiry.
وَقَالَ رَبُّكُمُ ادْعُونِي أَسْتَجِبْ لَكُمْ ۚ إِنَّ الَّذِينَ يَسْتَكْبِرُونَ عَنْ عِبَادَتِي سَيَدْخُلُونَ جَهَنَّمَ دَاخِرِينَ ﴿٦٠
And your Lord says, "Call upon Me; I will respond to you." Indeed, those who disdain My worship will enter Hell [rendered] contemptible. (60)
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