Your SPF record has a limit of 10 DNS Lookups. Every time you add a new ‘mechanism’ in your record, you require a new lookup. You need to use mechanisms to add new IP addresses.
How to Fix Too Many DNS Lookups?
Resolve SPF Errors with One Click Automatic PowerSPF
Introducing PowerSPF record, the one-click auto AutoSPF DNS record optimizer tool. Enjoy error free SPF record and manage unlimited SPF records easily. Solve SPF 10 DNS lookup limitation issue, authorize email sending sources.