If emphasizing quantity:
* Abundant: "There was abundant evidence to support his claim."
* A great deal of: "A great deal of time and effort was required to complete the project."
* A vast amount of: "A vast amount of data was collected during the study."
* Heaps of: "Heaps of clothes were scattered around the room."
* Loads of: "Loads of people came to the party."
* Plenty of: "Plenty of food was available for everyone."
* A multitude of: "A multitude of challenges faced the team."
If emphasizing intensity:
* Extremely: "The film was extremely popular."
* Highly: "He was highly regarded in his field."
* Immensely: "I was immensely grateful for their help."
* Terribly: "I'm terribly sorry for the inconvenience."
* Enormously: "The project was enormously successful."
* Significantly: "The weather conditions significantly impacted the game."
If emphasizing degree:
* Very: "The room was very quiet."
* Quite: "The movie was quite enjoyable."
* Rather: "It was rather hot today."
* Fairly: "The instructions were fairly straightforward."
If emphasizing excess:
* Too much: "I ate too much cake."
* Overly: "He was overly concerned about his appearance."
* Excessively: "They were excessively loud."
Ultimately, the best replacement for "so much" will depend on the specific meaning you want to convey.