How to insert price adjustment after contract automatic renewal ?

 

 

We are using release 12.1.3.       Thanks to anyone who can help us on this topic :

Our Service Contracts are  automatically renewed, year after year, and the prices are updated using the “markup” field (we enter a percentage).

Unfortunately, we also have specific products covered by these contracts, where the standard yearly markup cannot be applied, we have to calculate a specific increasing percentage for these elements (mostly based on the aging of the product). For instance one contract line can cover about 20 products,  all of these sub-lines must be increased by 2% at renewal, except one of the covered product, which price should be increased by 5%.