I would leave it as is. "Organizing the reception" works well as an adverbial clause modifying "took". "While" works well: You deserve a medal for all the trouble you took while organizing the reception. Other possibilities "to organize", "by", "in" would also work well. Many more prepositions would work.

You don’t need to use a preposition : ‘ You deserve a medal for all the trouble you took organising the reception ’ is sufficient. However, if you choose to use a preposition the most suitable ones are ‘in’ and ‘over’.

“for” organizing the reception