Growing in Raised Beds
If you are considering adding the liners to your raised beds, I am afraid that you will need to dig out all of the soil to empty the beds. The liners can then be added and the soil replaced. I would add a generous amount of compost to the soil as you return it, to add some nutrient for the growing year ahead.
If you want to avoid emptying the beds, then it is time to give your beds a thorough dig over. If it is safe for you to do so, you can dig the beds in the traditional way by standing on them and using a spade or fork. This is how I tend to most of our raised beds at this time of year. Higher raised beds are dug over with a raised bed fork. The soil needs t be thoroughly turned over, as deep as you can manage it, to loosen the soil and ensure your vegetables have a deep root run. Then add generous amount of compost in order to improve the soil.
Make sure you try not to grow the same types of vegetables in the same bed as last year, wherever possible. If you are growing beans, peas, squash or brassicas and can source some well rotted manure, dig some into the soil now to further improve your soil. Root vegetables and salads will not appreciate the manure, but will enjoy it next year when it has thoroughly broken down. Carrots and parsnips will like some sharp sand added to give them a free run down through the soil.
With regards to your greenhouse, you can add some shading to the roof to try and prevent the temperatures from climbing quite so high. Peppers and aubergines will really appreciate the hot temperatures, but tomatoes and cucumbers will prefer it to be slightly cooler.
I hope this helps. As always, please let me know if I can help you further.
I wish you well with the growing season ahead.