I think you should always provide a way for user to go back and review the product detail from cart. The benefits are:
- Shoppers are able to review (again) the products before buying
- Provide a cart environment where the shopper doesn't feel "trapped" in and forced to buy
- Save user the trouble of finding alternative ways to go back to the product detail page if they wish to
- Provide a casual and open shopping experience to shoppers
Moreover, take a look at reputable e-commerce sites like Amazon, Zappos, Target, and Apple Store, who have invested countless money into UX, they all provide link back to product detail page from the cart. This trend among peers should also nudge your company in the direction of providing link back to product detail page.
The NNGroup also encourage providing a form of "return to shopping" link on the cart page. (Source: Nielsen Norman Group E-Commerce User Experience) They argue that:
There are several possible things a customer would like to do after verifying that an item is in the cart and noting the total purchase price...Accessorize the chosen items. The customer needs some suggestions about what other items might be needed, with a link to the product pages where the features of the additional items are shown.
Ultimately, you want to ask is cart abandonment caused by the link back or the price change? Most likely, in my opinion, it's the latter.