What is the meaning of 提提大家？
This question's answer will address two things.

the advantage of compound words (specific) over the single character words (general)

the function of the reduplicated verbs


提 as a single character verb can mean:

提起，提及 (mention)

提醒 (remind)

提示 (prompt)

提起 (lift; pick up)


Example:
別再提他了 = 別再提起他了 (Let's don't mention him again)
記得提他吃藥 = 記得提醒他吃藥 (remember to remind him to take medicine)
別提他，讓他自己想 = 別提示他，讓他自己想 (don't prompt him, let him think for himself)
提刀斬人 = 提起刀斬人 (pick up a blade and hack people)
It would be much more precise to use compound words 提起，提醒 and 提示 than using the single character verb 提.
A single character verb can be reduplicated to indicate 'briefly; in a slight degree or in a casual manner'
Example:
試學廣東話 = try to learn Cantonese
試試學廣東話 = try to learn Cantonese a little (briefly; in a slight degree or in a casual manner)
看電影，吃飯 = watch movies, eat dinner
看看電影， 吃吃飯 = watch some movies, eat some  dinner (indicate a casual manner)

提提大家 = (slightly; briefly) remind everyone


Example sentence:


提提大家，集會時間是晚上九時 = (slightly; briefly) remind everyone, the gathering time is 9:00 pm


It is the same as 稍為提醒大家，集會時間是晚上九時