I mulch the heck out of mine to keep weeds down. I wouldn’t use a weed killer in the bed. You can dig the live stems and till the bed, then re-plant and super mulch but you might not get a very good crop this year. I do the till/re-plant about every five or six years and add in some new canes to help keep genetics running pure.
Acidifying may help a little but I’d go really easy on it since the plants are established without the acid. The only thing I put in the raspberry bed is 10-10-10 fertilizer and that goes on in the late fall after the canes have been cut back.
I have a white pine in the yard that sheds bad. I till the needles into the garden to help keep the soil loose and it works wonders. In a raspberry bed they’d go a long ways in keeping weeds down if the blanket is heavy enough.