One easy way is to increase IP lease time in /etc/dnsmasq.conf file as follows.
Look for dhcp-range option, and change last value "12h" to "infinite" e.g. change
Another way of binding MAC and ip is by adding 'dhcp-host' entry in dnsmasq.conf file
Once dnsmasq.conf file is updated, restart dnsmasq service using
service dnsmasq restart