I have had an IKEA chaise lounge for a while. It has always been hard to do vacuum cleaning beneath it. Today I replaced the original legs with IKEA Sultan in oak. Easy to do and all you need is the four legs, four carriage bolts size M8 and screw-nuts. Washers are supplied with the legs and you can use them.
Drill holes in the frame beneath the cover, insert the bolts, attach the legs and tighten the nuts. Done! Time less than 30 min including clean up.