first of all, it does need to be like this. homekit binding can run stable for a long time without restart. e.g. i have restarted it last time 6 months ago and only because of an upgrade of openhab.
so, it is possible to get it stable.
lost connection or items with no response could have different reasons.
few things to check:
in main ui, go to homekit settings and change the “Use openHAB mDNS service” setting. if it was OFF, make it ON or otherway around. it should make homekit immediately visible again, without restart, and sometimes it makes the connection more stable
install app “discovery” on your mobile and check whether you can see “_hap” in the list and which IP address you see assigned to it. it should be ipv4 address and should not change over time
see here for instructions HomeKit Add-on - System Integrations | openHAB