My sofa is disgusting. Tips for cleaning please

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Before we had children dp and I bought a white (I know I know!) ektorp sofa from ikea.

Fast forward 6 years and 2 dcs later and the sofa covers are disgusting. They are washable and I try to do them once every 6 months or so and use throws on the sofa; but ds and dd seem hell bent on covering the sofa in as much stuff as possible. At the stage now where washing doesn't get all the previous stains out.

Anyone have any thoughts? Can't really afford to spend £200 ish to get new.covers (can get white ones again cheaper but seems a bit silly)

Have thought about dying the covers myself? And a slightly odd question but if I threw some bleach into the machine with the covers would that help with stain removal or just leave my covers a weird colour?

Apologies for the dull topic

I tried cleaning my ektorp covers with bleach in the machine, I didn't find it made much difference, but it didn't damage them either. The best thing I found for getting the stains out was to make up a concentrated solution of hot water and biological washing powder (I think I chucked in some napisan as well) and I got a scrubbing brush and scrubbed the individual stains well before putting the cover sin the machine to wash. That got out pretty much everything except ds2 soya milkshake stain.

I have also dyed some ektorp covers in the machine with the dylon fabric dye. I found it worked very well and I will probably do it again. I dyed my 2 seater covers. I did the main frame cover on it's own with one box of dye, and then the 4 cushion covers with another box.