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.

She replied:

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.