There is a very well-known and powerful dua we should recite for Laylat ul Qadr. Check it out here. It is in English and Arabic.
Aisha [may Allah be pleased with her] was asked what the Prophet Muhammad ﷺ supplicated during the last ten days of Ramadan.
اللَّهُمَّ إِنَّكَ عَفُوٌ تُحِبُّ الْعَفْوَ فَاعْفُ عَنِّي
Allahumma innaka `Afuwwun TuHibbul `Afwa Fa`fu `Annii.
‘O Allah, you are the Forgiver, You love to forgive, so forgive me.’
– Musnad Ahmad, Sunan ibn Majah and at-Tirmidhi.The Prophet (pbuh) also gave us a tip on how to spot laylat ul Qadr.